I ran an 870 for quite a few years, and the g/f is currently running a Nova (in 20ga). You don't have to buy a new barrel, finding a used one is not too hard. As for the action bar issue, at least what I remember of the issue, I keep my mag springs a bit tight, so the whole "bouncing shells" does not appear to happen (to me, yes I am slow). At the time, I was also using pretty light loads, rolling my own so my young boys could use their shortened 870. I cannot run the Nova nearly as fast as my 870. However, I do really like the shell feed lock out that is on the Nova (although a bit of a novel idea). With some practice, my g/f has found she can hit that while ejecting, put in a slug, close, and put in another slug (mag tube), for those pesky slug targets in a bunch of shot ones.
Maybe consider buying a used 870. I have bought several at pawn shops for well under $200.. The Nova is nice!!