Thanks

Double checking on Wikipedia..... the "Ratchet & Clank Future" series on PS3 was a new storyline, so there shouldn't be any story gaps from Size Matters. As for Quest for Booty..... honestly, I was unaware that game existed. I just played ToD and CiT one after the other and it seemed fine to me.
(Wikipedia says Quest for Booty is a PSN title, so it shouldn't be very large/expensive, I'd think. But that's just a guess.)