...is there any reason to glFlush() as well? I don't seem to need to, and by the name you'd think I wouldn't have to, but I've just been looking at some code that does both (with a glFinish() to boot), and I was wondering if there was any reason to.

You should neither glFlush() nor glFinish() if you have a double-buffered context. The glFlush() will be a relatively cheap no-op (since CGLFlushDrawable() will call that for you); the glFinish() will be very expensive, because it won't return until all your rendering is done.

Cheers. I've been avoiding glFinish() anyway.