No.
It's still a major investment of our research capacity.
But worth it, I would say. If only for logistics. We have unlimited energy. Normal materials are abundant in asteroids. Eezo is rare, and is the logistics chokepoint. It has to be mined in hard to reach places. Artificial eezo completely negates that issue.
And, in a war against Reapers, lack of infrastructure to hit (or, rather, lack of long logistical chains to cut) is going to be very important.
...
Making artificial eezo is a 64000 point tech. Stuck behind 3rd generation arc reactors, which is another 16k points down the line. And we have no idea as to the efficiency of the production of artificial element zero. It could collapse the eezo market, sure.
First of all, you are an order of magnitude off in RP counting. As to efficiency - I assume that, just like any other tech on our techtree, the development means "it's now economically viable to produce eezo, rather than mine it".
It could also shave 10% off the cost of ships. Which is, on a galactic economy scale, a lot of money, but when you want to turn the entire population of the galaxy into space nomads it's frankly not enough of a margin, or even just humanity. Not when we've never actually seen the properly settled regions of human space instead of startup colonies, the fringes and temporary base camps except from a distance, nor have we seen in Mass Effect the full extent of the socio-economic ramifications of one and a half centuries of further development and automation, as well as access to the mineral wealth of space.
There are basically no "properly settled" human planets except for Earth, from what I understand.
... Space is large, yes. There's also a lot Reapers, and they can use the Relay Network to move far faster than that fleet ever could on the strategic level, while if the refugees try it it's a big red flag for the Reapers to pounce on.
Space is mind-boggingly large, and if we stay away from relay systems (for example, moving perpendicular to the galactic plane), there's no way they'll find us. FTL sensors aren't really a thing.
Um, not really? The problem here is the supremacy of offense; if nothing else, the Reapers can decide "fuck it" and nova-bomb the sun around which your super-expensive orbital ringed planet is orbiting; we don't really have any tech that can survive a close-range supernova. Really the best we can hope for if we can't either diplomance our way out of the problem, or possibly out von-Neumann the Reapers by making friends with the Geth, is to delay long enough to evacuate the garden worlds and settle into what amounts to an eternal cat-and-mouse game where our ships shred each others' and build new attack ships out of the enemy's debris. That's a process which will take decades even with a decisive technological advantage, given that the Reapers are going to out-number us hundreds or even thousands to one in the best case scenario. Any orbital rings or other massive fortresses built around planets will be long since converted into expanding clouds of vapor by then.
Space stations, however, might be a good investment. You could place them in deep space (even if they aren't really mobile themselves) away from potential nova bombs.
Because, yeah, nova bombs are the biggest strategic danger here.
