LMC as with most other supply houses, do not (or have very little) to do with the actual manufacturing process, so that is likely where most of the problems stem from. With that said I have made two trips to LMC in person and Classic parts in Riverside and have dropped a lot of money both times at both places. Between me and two friends I think it was at least 7k+ in parts from both combined.
LMC premium 73-84 bed header panel- Very nice
Triplus or keyparts? 76-80 Chevy Premium tailgate- Very nice
Triplus 75-76 Bowtie grille- Very nice
75-78 headlight bezels, very nice but plastic (how all aftermarket are)
LMC premium fenders- very good
From classic parts
longbed bed floor- looks good, have not installed/fitted yet.
shortbed sides, look good
premium 73-78 hood, very crisp
I will add this too- Since squarebodys have become much more than just $500 beater trucks, the market has gone up on them, thus driven the aftermarket into developing premium quality tooling and obtaining licensing for branded grilles, tailgates, etc. Whereas the gap between GM selling their own replacement parts and premium aftermarket parts, was heavily populated with fits enough crash parts.
Look at what Auto Metal Direct has/is doing, they are working on and releasing new updated tooling and selling parts that either haven't been available before (or for some time), or creating new stamping dies to make better fitting and quality parts. Since die/mold work is anything but cheap, prices of course reflect that.