I see no reason to regulate this at the class level. As long as we maintain that both configurations can race on a level rating, we have no basis on which to argue that changing configuration mid-regatta creates anything other than fair competition. The suggestion some have made that they would be happier two-up in heavy weather at this point is purely anecdotal. If someone wants to collect some data that suggests a performance differential either way under some conditions then that's fine and we can evaluate it at that time. In the meantime, if someone wants to sail with a friend who is only available for one day of a two day regatta, this is a strength of the class, and we should not, as a default position, make these people feel they have to bend the rules to do it.

OTOH, if a particular event wants to regulate against this, I think that's also fine, and I think a rational case can be made for doing so - if you award a trophy to a boat that switched configurations, is the trophy being awarded to just the skipper even though s/he wasn't solo for the whole event, or to the skipper and the crew even though the crew didn't compete for the whole event? I think an event organizer is entitled to take the view that that's not a scenario they want to face. But for the weekend warrior who's personal goal is to just improve on his or her best fleet position for the season, sure it may all be in fun, but people like to feel they are following the rules - and indeed part of the satisfaction is in doing so. I see no reason to impose restrictions that limit the opportunity for people at the grass roots to enjoy the sport.