Re: monolithic v. polylithic uppers
I have a LMT CQB MRP, Its well crafted. Accurate for a 16 inch crome lined barrel. The only great advantage I love about it is the ability to remove the barrel and swap to other barrels and cleaning is a breeze. I take the barrel out about every 4th cleaning.
It is nice that the upper has one solid rail. But I bought it for the removal of the barrel and the craftmanship.
If you look at the GAP 10's their uppers and lowers are built for them by POF I believe. I dont think It matters if its a monolithic, or non solid upper. I think It matters who built it and how well they built it.
I'm sure some one with more knowledge and experience will chime in on the subject. But this is just my thoughts on the subject.