I've decided to quit the rental habit and buy some scuba gear for my dive vacations. Unfortunately my LDS is not very local with a limited selection so I can't put on my dive boot and expect to try on open heel fins that I've read good reviews about so I'll be ordering fins online. I have 5mm Cressi Ultraspan boots size S (I'm a 7/39/25 in US/EU/JP sizes) and I'm looking at the Aeris Accel, Hollis F1 or F2 or Poeidon Tridents. Should I order the same size as my shoe or should I expect to go up a size if I'm using boots with a fairly thick sole and not dive socks?