12s3p 26650 is a lot. Very bulky. 12s gives roughly 10s equivalent voltage. 14s is worth considering.
I’m running 3 boards with A123. 12s1p china hubs, 12s2p 2x6355, 15s2p hummie hubs. I do get some sag, and wish I did 14s2p on the 6355 build. But it’s okay with 12s.
And +1 to everything b264 said. But I’ll make a distinction between generic lifepo4 and A123.