my 2 cents...
if you ultimately want a carpet anemone i would start with a carpet anemone.
however, if you're going to start with a carpet anemone i think you have to do a lot more homework before you get an anemone. regardless of what you start with, IMO, the first time you get a carpet is going to be a unique experience, even if you've kept BTAs or LTAs before, so i don't think keeping those gives you that much of an edge if you don't do your research and learn the proper husbandry for a carpet. again, i think if you want a carpet, go for it, but you have to do much more homework and be prepared to be much more thoughtful about your husbandry if you do.