We purchased a new 2551 in April with the new sofa/air bed. When we were shopping for the RV, we had an opportunity to sit in one with the old electric fold-out sofa and the new sofa/air bed. We found that the new sofa is much more comfortable to sit on and it sticks out 6 or 8 inches less than the old one when in the sofa position, a big difference considering the room available.
We slept on the air bed once and it is ok - not great, but it is for the grandkids and they think it is great. We are really happy with the new one for sitting comfort and more floor space.
Hope this helps,
Bob