Also, atm, I'm considering going for concrete huts or not. I'm at 10 paragon and 6 karma (reset at 80 kittens), and reaching 125K science seems a lot. It would seem I'd need to get around 40 observatory to do that (with some biolabs on the side), and I fear it might take a looot of time to do that.
It might be easier to advise you with more information, but very probably yes, going for concrete huts will be worthwhile. The cost reduction is worth more than it looks like because it's applied as the base of an exponent. 2 ^ 10 = 1024, but if you apply a 30% reduction to 2, 1.4^10 ~ 29. It might be reasonable to expect 10 more kittens solely from that one upgrade and a couple hours of farming wood.
Be sure you have astrolabe and titanium reflectors. They'll help.
Also, trade ships increase the amount of titanium you get from zebra trades. Titanium being the usual bottleneck for both mansions and the alloy needed for biolabs. You might end up with more biolabs than you'd expect. And Iron is usually the bottleneck for observatories, and the zebra trade gives that too.
Finally, don't underestimate the value of simply grinding our more log houses before a reset. It's boring, but I've had runs where simply waiting around an extra day past the point I felt ready to reset in order to get those "couple extra kittens" resulted in 20+ more kittens.
110-120 kittens is a very attainable number for a second run.