Pete,

I don't want to name names, but there are definitely some devices out there which behave better with slower DMX, but the downside is, the good ones which can do smoother fades at 44Hz will lose their advantage. That's why having variety and letting the user pick is good.

You can design down to the lowest common denominator if you like, but I'm an advocate of giving the user some options. Around 3 sounds easy to think about and discuss quickly, from a GUI point of view, but as someone who is constantly taking support calls from users who wonder why their particular lights which are cheap Pacific Rim knock-offs don't respond well to rock solid DMX512 compliant signal... the more you can drill down and tweak, the better.