Every finish nailer I use needs a driver assembly every 50-60,000 nails. Seems reasonable to me, can't expect any nail gun to last forever without maintenance. The triggers also get finicky but I clean them with electric cleaner and put some dielectric grease in. Haven't had one have a problem after that.
I'm sure a lot of guns go back for warranty because of these issues. I can't wait for DeWalt to replace them so I just fix them myself. The trigger is an easy and cheap fix and drive blades are just a wear item.