to me, the difference between DL and B6 is pretty big. Having free fast wifi, unlimited tv is pretty big deal and same with the extra leg room especially in EMS. And I don't have to deal with RJ.
Btw, I would expect A220 to be a really great experience. The leg room should be the same as E90 and reconfigured A320. Still holding out for TATL A220 at some point. Maybe they will get the XLR version. I don't see an all mint version, but more of a mini-mint cabin for places will less premium demand.
Moulder3, by all account, A220 is a great experience and B6 version should have great leg room. Give it a chance when it comes out. I'm sure you will like it. My only regret is that they are not getting one until end of 2020.