If the "benefits" you are talking about are mutual (and seems like they are), you are technically using each other, not just he -- you.
Excellent point. My post on this thread was intended if you weren't interested in being used or using people and wanted a genuine LT relationship. Now that the "friends with benefits" has come into play then it's really up to you. Yes he might be using you, but you'll be doing the same, wouldn't you? And don't even think that there's such a thing as "exclusive friends with benefits". Cause if you are just friends, he's free to date whomever he wants in addition to playing around with you.
Alexi