Down side to stripped lowers no warranty other than right when you buy it I haven't seen any company that would do anything once it's wrenched on
as far as lowers go if your building a regular rifle and not worried about a rdias or anything else I'd buy what ever is cheapest local
down side to mail ordering a lower is shipping and transfer fees there are a few dealers around that still do cheap transfers (10-15) but most charge 35 and up
I've built on colt, spikes, bushy, RRA, LRA, DPMS, aero, AE, Mega, Sun Devil ......
no real difference other than the pic on the side and some finish color I did like the spikes and mega as they had threaded holes for the rear detent spring