Things is they don't actually give you a ticket, they usher you through a sliding door from the restaurant into the club. Another reason we stopped doing the Pacha dinner thing was the introduction to the set times, bit of a ball ache as like you say it's either just a tad too early for staying and going into the club or it's a bit late for having a meal and feeling all full.
Maybe someone on here can elaborate on a hand stamp, leave then come back in? I honestly can't remember getting hand stamped when going from restaurant to club and it's been a good few years since we bought a ticket just for club access so can't even comment on getting a hand stamp on entry.
Also 6 might be border line a bit early for Rumours, I'd say it was still mostly day guests / residents at that time who were still enjoying a bit of sun / pool time.