I love the 8.4" screen in my Dart. I know it's getting up there in age and maybe the new ones are different, but I have close to 100K miles on the 6 year old car and never have had any problems with my 8.4" other than the screen locking in phone mode a few times when I try to make a call not noticing I was in an area where I was getting no bars (can't get back to the regular screen until turning phone off, or shutting car off or some combination of messing around).
I want to get a Ram and have been looking at the options. I can't imagine a need for the 12" screen, it's like having a big screen TV on the dash!