Nice pace here - nice and easy does it; a slow buildup to a satisfying climax (or three).
So let me cast my vote in favor of the triple.
As far as "the talk" in the pub I can see it starting off with Remus, then, just as Harry is getting comfortable with the idea of intimacy have Dan “happen” by. Followed too soon by Xeno and then Alistor - who would insist on casting a broad-spectrum "finite" on the girl to make sure she wasn't imperioused (never mind that such an action would negate any contraceptive spells, that’s what condoms are for). Just when it looks like it couldn’t get any more uncomfortable for our hero have Tonks put in her tuppance worth (or two knuts worth) so that it ultimately becomes an open forum a la’ Dr. Phil in the bar snowballing out of control as Harry tries to make himself smaller, and smaller. . .
Oh we love to torture our hero, don’t we?
N!