I've removed the last rule, any iso is fine. so go ahead and use iso1600 or 3200 i dun care, but dun complain if you exchange it for a cheapo iso200 film
how we do it:
when everyone meetup, we'll throw all the film into a plastic bag, then we lucky draw our film. no choosing. this is to be fair. if you get a high or low iso film that your camera can't use, then too bad.
at the end of the day take home original roll or the exchanged roll?