I am flying Delta in September (MAN-ATL-TPA).
Although I have flown Delta before, I don't recall it being on an MD11 (as it is this time).
I love Virgin, but couldn't get the flights this time.
The MD11 is a 'fairly old' aircraft and I doubt it will have such features as seatback tvs etc. However, I think you will have an inch or two more legroom than on Virgin.
Virgin service is, IMHO, superior to that of BA, Delta and the charter operators.