There have been some reports of non-existent QC on early production. Supposedly they are slowly heading in the right direction. Discounting that they do not come from the shop of the man himself, which probably counts for a lot, the main difference between the Forbes and NULA is the Forbes uses an E.R. Shaw barrel instead of a Douglas like the NULA. E.R. Shaw barrels are comparable to what you get with an ordinary mass produced rifle. Douglas is top shelf and has a proven track record of working when bedded in Mr. Forbes' stock.
I don't have any real world time in the field with one, but once the negative reports stop coming from those that do, I expect to.