I have a couple of their setups and never had an issue, reliable and well made. Only issue is more weight up front, but a lot less gas blowback with a suppressor.
I put a few thousand rounds on one of their add on kits. I think the timing was a little faster due to the mechanical linkage. My brass was alway a little dirtier and the pop from the ejection port seemed louder than with my rifle length gas DI guns. i sold it and moved to a tube and adjustable gas block.
I did a build a few years back with the Superlative Arms kit, and they were excellent, and accessible by phone for support as well. Never had a misfeed with it either, no matter what I have fed it.