Would you like Erik to chose between 4x4x4 and 5x5x5? Or Edouard between 2x2x2 and 3x3x3?
No, those are short. I would like Michael to pick between 20x20x20 an 21x21x21, though...
I already have to give up FMC for my 4x4x4 BLD attempts (not that I do much FMC, but if I didn't have to give it up, I would certainly focus on beating the NR)...
Z2, I think, may discriminate among events.
I think that the WCA-imposed limit is rather non-sensical (same with the 10/cube). Ron's main argument is that it allows the organizers to handle competitions better, and that it makes the event more fair for everyone around the world.
Why not allow the organizers to decide? If they can handle it logistically, then why stop them? Ron claims that the huge number of registered multi competitors at Euros will cause trouble. But then why not declare limits only for that competition?
As for bias among competitions, note that competition distributions are already unfair by proximity, continent (comps on the same continent tend to handle things similarly - you can't do foot-solving in the US...), etc. Chris Brownlee has had a great chance at breaking the megaminx WR for the last few years, but has not had a competition opportunity anywhere for it.
Multi, if someone cares for it enough, could easily be a single dedication for a competition. With the point system, it's not even the same risk it once was.
And if you have to miss other events, especially BLD events, why not just put give the competitor the choice to take her/his attempts immediately before multi?
If Tim wants his 1-hour limit, propose a new event: Have the competitor memorize cubes, requesting/drawing them from the judge in order. After at most one hour, the competitor must don the blindfold and solve as many as (s)hehas memorized, in a "reasonable" time.