I am going to be even harsher than Musicman. The R51 feels TERRIBLE. I never got a chance to try the 1st gen so I can't speak on the difference. The new one just feels like crap. The grip safety is very gritty when squeezed and just kind of sounds like metal scraping on metal. The trigger is meh. There is no sound or feel of the reset on the trigger after it's pulled. if this is the second gen, God forgive who ever designed the 1st gen.
I have also noticed what musicman mentioned too. We see 870's with rust on them straight out of the box, not surface rust but rust under the finish. One of the guys in the store purchased a 770 chambered in 270 and said that it struggles with ejecting the empty brass. He had to resort to slamming the rifles butt down while pulling on the bolt to get it to eject the brass the other day.