I feel pretty vindicated in not choosing torpedoes after seeing how the Saladin turned out and that final science stat on the Kea is straight up monstrous (nearly twice the Sagarmatha's).
The Kea managed to do several times the work of the Saladin's despite having 3/4 of the number of hulls and managed to not just stay in service about 20 more years (~60 vs ~80 years) but spent it's whole service life as a science vessel which itself is more than twice as long as how long the Saladin spent as a science ship (~30 years)
The Saladin accomplished vital industrial work in its dilithium prospecting missions, very much paying for their own warp engines, but after 2240 the shortcomings of their single-nacelle design and lesser capabilities effectively removed their status as a science ship only three decades after their launch.
Despite that though, the sheer number of Saladin's that were pumped out (a solid 1/3rd more than the Kea) shows that there was a significant appetite for science vessels that even the non-torpedo Kea couldn't fulfil, much less an even more expensive torpedo-Kea.
I also do not think that a torpedo-Kea's greater tactical capabilities would have been able to justify Starfleet deciding to produce it solely and in greater numbers since the primary reason for the Saladin's development was due to cost, not because of tactical deficiencies.
…the competency of the Kea-class was not in question, and when the prototype underwent trials in 2211 it was clear that it represented the absolute state-of-the-art in scientific capability. But its sheer size and expense, even with the cost-cutting measures inherent in its design, prompted consideration of other designs by Starfleet Command.
The cost and time (the Kea took twice as long to produce) of pumping out additional torpedo-Kea's to match the Saladin hulls 1 for one (because again, the demand for more science vessels was there) is just too great so it is likely that Starfleet would still need a cheaper science vessel to fill in the gaps left by the now even costlier Kea.
If I had to speculate the most likely outcome for a counterpart to the torpedo-Kea would probably be a spammable and underarmed frigate weight science ship (the other science ship option we were given) for internal surveys instead of another cruiser since a more well armed Kea would cover all the tactical needs the frontier demanded (it would probably still have been pulled off of frontier duty at around the same time as the Saladin due to similar tactical scores).
Interestingly, since the Saladin clocks in at 180,000 tons it's hull would actually qualify for this role as the cutoff for the frigate's mass was 200,000 tons. You'd just need to strip off the majority of the weapons the Saladin had to make more space for science facilities since I doubt you'd be able to afford the same armaments given the industry demands of a torpedo-Kea.
I'm doubt however that such a ship would be anywhere near as survivable as the Kea (9/12 of the Kea's managed to survive the Klingon war which is pretty solid majority) which may lead to some longevity issues since I'm pretty certain a spammable underarmed frigate would not have the firepower or durability to ward off even a single BoP (they may just get popped by an ambushing cloaked BoP's alpha) and may not be able to run away at warp as quickly as the Kea could given how much slower the Saladin turned out (can't even hit warp 7 when sprinting) in order to make it even more affordable than the Kea.
Regardless though, a hypothetical torpedo-Kea would have still been retired around the same time as its non-torpedo counterpart since it's science facilities would be the exact same while the additional torpedoes wouldn't change the fact that it would still be woefully obsolete as a combatant at the time of it's retirement (the Saladin by the Klingon war was already obsolescent, much less what another 20 years would entail).
Even if we go with the optimistic route of Starfleet deciding to only build torpedo-Kea's the selling point of its tactical prowess wouldn't have payed off since by the time of the Klingon war it would have been obsolescent and the OTL Kea's which did get refitted with torpedoes in 2240 didn't seem to have distinguished themselves during the war.
The Kea-class underwent a retrofit in 2240 to install a pair of forward torpedoes and lost its dilithium-analysis suite in favour of an expansion of its antimatter reserves, turning the ship into a budget heavy cruiser. The anticipated hostilities with the Klingons did not materialise as soon as expected, and the nine ships that survived the Federation-Klingon War two decades later continued in service until 2270 when they underwent a full refit as part of the Fleet Modernisation Program.
On the flipside, I'm not sure if we could even design a ship that would have satisfied all of Starfleet's needs enough to justify building just one class of science ship.
The Saladin compromised a lot on science facilities (science stat of 9 is worse than the 35 year old Sagamartha's 10 and less than half the Kea's rating of
19) since it didn't bother with a separate engineering section so it had less room overall for facilities. This meant not just fewer facilities to boost science and engineering stat overall but also fewer chances for synergistic combos to inflate those stats even further or in the Saladin's case give it a non terrible rating (seriously, the Saladin's science and engineering stats look
terrible by comparison as both stat are either
half or less than half the Kea's stat and an aggregate of those stats between the total hulls of each class produced would see the Saladin behind by a lot).
Without a separate engineering section to increase available space, the Saladin-class was much more limited in scientific terms.
Sacrificing the engineering section did however give it medium maneuverability without needing to break the bank and without that medium maneuverability the benefits of the torpedo launchers would have been way lower.
To put it into perspective, if we had gone with 2 torpedoes and 4 phasers for the Kea (which would have still costed more industry than the Saladin) which would give it 75% phaser coverage, equal alpha strike, and double the Saladin's multi-target rating (8 vs 4) it would have still been a whole grade worse in tactical rating than the Saladin thanks to the Saladin's medium vs the Kea's low maneuverability.
Basically, it seems like with a cruiser weight science vessel at our current level of tech we have to make compromises and settle for either few and costly but high performance or numerous and cheap but mediocre to outright bad (that 9 science stat is painful even if A- tactical is nice) but Starfleet required both capable and numerous science vessels so they ended up going with two different options at the same time.
Overall though, I think this was the best outcome. The Kea put in a ton of work and it has had one of the longest service lives out of all our designs. It managed to strike a good balance between it's primary role of being a science vessel while remaining survivable enough that the majority of the class endured the Klingon war. While the Saladin's that came about as a counterpart did suffer some serious casualties I'd take Starfleet having all of their science ships be at a bare minimum decent combatants as a good end result.