Can't go wrong with a Defender lower . Having said that don't assume that because both are LMT they will be a better fit
I have a RRA lower that is rock solid tight ( takes is bit of pushing to get the takedown pin out ) to 3 of my RRA upper. Using my LMT Defender these uppers are also tight (no wiggle ). They also fit great to my Vltor upper
I have a LMT MRP upper that is not even close in color match to my LMT Defender lower and is so sloppy it rattles. The anodizing on the MRP is purple. This is suprising the LMT MRP, being a $1300 precision machine monolithic upper is the sloppies fit out of all my uppers on the LMT Defender lower ( not that it really matters, its just annoying after you spend that kind of $$ ). Go figure
Between all my other lowers and the Defender , my next lower will be a LMT. I would suggest the SOPMOD stock with standard trigger and then replacing the trigger with an aftermarket. For the extra $$ that LMT wants for their 2 stage I would put that towards a Geissele or similar
