A search on Delta's website on the Economy Comfort page doesn't mention the regional jets. It would be nice but i wouldn't bet money on it.
As far as the utility of economy comfort in general, it does make a difference in the seat pitch versus the typical Delta economy seat. Sadly for me, Economy Comfort is still a disappointment. As my /nick suggests, I'm of extreme height and flying generally sucks for someone like me. The irony is that I have to fly enough that I'm Diamond Medallion. Over the last two decades, I've watched the seat pitch in first class domestic flights shrink from comfortable for me to cramped (meaning the seat in front of me is either touching or almost touching my knees. Regular economy seats are "not flyable".
Recently I actually had to do it since I was traveling with my special needs son and so I turned down my regular upgrade but wasn't able to get a bulkhead seat like I normally do in that situation (the Delta F/As on the flight were so unhelpful that I named them all in a stern letter to Delta...my first letter like that in 25 years of flying). My legs had to bow outward at an extreme angle, intruding on my son't space and the poor woman next to me (I was in the middle seat). I still have some lingering nerve damage from the 3+ hour BOS
flight. Economy Comfort would have helped on that flight, I admit.
But recently I took a 767-300 from Atlanta to Zurich and I was in Economy Comfort. Since it was my first time in EC
, I was hopeful it was going to be enough for the 10 hour trip. Given my knees were hitting the seat in front of me, I wound up having to trade my aisle seat for a bulkhead middle just so I could rest and sleep on the plane and not inconvenience the poor guy unlucky enough to have a seat in front of me.
Bottom line....Economy Comfort is nice to have but won't change my flying habits in coach unless I'm in an extreme situation, like with my son. It still needs another 1-2 inches of seat pitch...but then again, so do all Delta first class seats. For me, seat selection is exit row, bulkhead, first class or "when's the next flight?"