I've flown VS Economy Delight a number of times. It will credit correctly and booking class will be 'V'. VS uses coach fare basis codes for Economy Delight fares just like DL uses for C+ and BE fares. The second to last character in the fare basis code is a 'C' which means you have an Economy Delight fare (they also use 'I') that books into V. DL C+ fares will also have a C or I as second to last character in fare basis code and book into DL W and S classes. There is a dual inventory check on these fares. There must be inventory in both the booking class and underlying coach class from first letter of fare basis code. It enables them to have a range of fares for Economy Delight, C+, and BE (corresponding to the various main cabin fares) while only having one or two booking classes to work with (as there are only so many letters in the alphabet).