I understand. Its tough to cut the BS.
Fact is, the lower of an AR is the lowest stress part on the gun. You can make functioning lowers by sandwiching two pieces of derlin, or even out of a block of wood. It has been done. Total fact... Yet people will tell you an expensive forged lower is a wothwhile upgrade. I cant see how - especially when you consider how few manufacturors of lowers are out there; half a dozen maybe. Most brands of AR are just rifle assemblers, who outsource the actual production to a small handfull of foundrys.
Uppers are even more of a joke. There are even fewer makers of uppers than lowers. I cant help but laugh at the ranking lists for ARs because of this. They are all purchased from the same few foundrys as the next guys.
The only major difference is the internals - and thent its mostly in QC testing. More expensive parts undergo a regiment of magnetic testing. Having this done for you turns a $700 rifle into a $1000 rifle ... even though a spare parts kit is only $75. Talk about getting taken.
DPMS is just fine.