You can always settle for cheaper (as opposed to less expensive), however MAYBE in the future you'll be able to get additional credits in an FTD.
Pt.135 operators who went out and paid millions of dollars for those FTDs are now reverting to using their competitors Level D FFSs because of the additional credits.
Also, at least one modern medium twin airframe has as many as 7 Level D FFSs, versus one Level B (regarding which I hear scathing fitness reports). Why isn't everyone going the cheaper way?
BTW do you happen to know of any airline actually using FTDs versus FFSs for pilot qualification?