I have 3 zips, all 4 F&F bodies the cobra and crusier.
I don't have a bit yet(45mhz supra in the mail) but I have tested a couple of microsizers and I must say that I wasn't all that impressed. I keep hearing the vast speed difference between the cars stock but I really didn't see it.
I got into these micros because of the portability and have fun modding them as well as racing them. I think all this hype is silly. If you have a bit, microsizer, zip or a clone, just enjoy it and stop whining like little kids "mine is better than yours!!!"
Everybody needs to calm down. If your not happy with speed or range or detail then do something about it.