DuracellEnergizer said:

but is in fact the height of obsessive, fruitless fanboy obscurantism because it's all an elaborate solution in search of a puzzle.

"Ben" being the alias isn't any more-or-less an elaborate solution than "Obi-Wan" being the alias.

Yup. The fact that only Luke and Owen (and I guess Leia once) seem to know "Ben" by that name would imply that it is the alias (as opposed to Obi-Wan which is what everyone - those three people plus Vader, Tarkin and Yoda - know him by).

Obviously it's not explicitly stated so it's open a little to interpretation (read: subjective opinions) but if you ask me Occam's Razor says that Ben is the alias.