The generalized rundown on cruiser vs explorer is:
1. For equal frame size, presuming that both designs max out the frame, cruisers will always beat out explorers in stats. This is just the way our system works. The margin by which they beat out explorers depends but because of how the system is set up, cruiser have more subframe room in the cramped subframes (Tactical, Operations, and Hull) while explorers have less subframe room in those subframes. This will not change with research. It just is how we differentiate ship classes.
2. For equal frame size, presuming both designs are optimized similarly, cruisers will always beat out explorers in build time. The reduction in build time for a cruiser is approximately 0.5 years to 1 year for the exact same sized ship. However explorers that have been optimized to longer build times in exchange for lower crew costs may be even longer in build time. This will not change with research either. However, it's possible that build time reductions make this kind of screwy.
3. For equal frame size, presuming both designs are optimized similarly, explorers will always beat out cruisers in crew cost. Crew cost is dependent on frame and subframe modifiers and frame size. Explorers have far lower subframe modifiers for crew. This hasn't changed with any of the research tiers we've done so far.
4. For equal frame size, cruisers will usually beat explorers in SR expenditure. SR expenditure however does depend more on exact parts than on subframe modifier, and as such is more variable. And since part SR cost varies with tier and part availability, it is harder to predict. Generally speaking more modern parts have a worse SR cost. The BR:SR ratio becomes more slanted towards SR the more we want to implement newer parts. However, it seems likely that cruisers will hold their advantage in SR over explorers no matter what.
5. The "sweet spot" for explorer design is way above the weight for a light explorer. When we talk about the sweet spot for class design, we mean the point at which adding more parts suitable for that ship approaches unacceptable diminishing returns. A light explorer is going to use a 1800kt or maybe a 2100kt frame. At these frame sizes, the subframe size is the limiting factor, not diminishing returns on more parts, and the essential weight components of the ship take up a relatively higher percentage of the ship so there is less room for more parts.
6. The "sweet spot" for cruiser design is somewhere from 1500kt to 2000kt, in the range for a heavy cruiser. The more lenient cruiser subframes mean that we can approach diminishing returns with parts a little easier than on an explorer, and the essential components of the cruiser take up a relatively lower percentage of the ship.
As an aside, it seems like the sweet spot for frigate design is in the larger end of the frigate sizes, about 900kt to 1200kt.
What this produces is a strange paradigm where slightly smaller cruisers can approach the stats of optimized explorers that are slightly bigger. For example, we have a 7/7/6/7/7/7 light explorer design on the 1800kt frame optimized for crew saving with 3/3/3 crew cost, yes you read the right, 3/3/3. However, a cruiser on the 1500kt frame could be 7/7/6/7/7/5 with 3/5/4 crew cost and yet as you can see it is 300kt smaller.
The problem with cruisers, however, is that the crew factor is MASSIVE and it multiplies with the frame size. So on the lower end of ~1500kt, you might be lucky to have a 3/5/4 crew, and on the higher end towards 1800kt you'll be looking at 4/6/5 or so, and because the subframes have these huge enlisted cost modifiers it just can't be reduced much at all. This is a really big deal, and it's why we haven't liked cruisers much in the past, but if we're looking at our build sheet and we've fingered a big crew surplus? Then we should really consider the cruiser even if it has a 6-enlisted cost.
I should mention doctrine just to say I don't think doctrine is the most relevant consideration. Our doctrine bonuses for explorers aren't enough that we can justify a light explorer over a heavy cruiser on doctrine alone. -2C and 5pp are the big bonuses, but 5pp is quite small in the grand scheme of things and this project isn't going to eat too much combat cap in comparison to things like the Excelsior refit or the Ambassador.
I'll get together a few ship comparisons but it'll take me some time.
