There are beveled allen head bolts. That is what I have, and honestly, when you need to pull the side cover off to do a clutch, you're not going to care how they look, you're going to care if they come off easily. You can use an impact driver to tighten/loosen them, but my roommate's Makita impact with the allen on the end can do the big cover on my 350 twin in about a minute, if that.
like Bob said,
Function>Form
Steve