I get what you mean. I've been doing some reading on the Zoom G3 and it looks like a nice unit, but if you're using an amp model that leaves only 2 spots for effects. It's probably better to have a little more room to stretch out than to butt up against the ceiling just a little too much. The whole trick with modeling (IMO) is that the technology is constantly progressing, so equipment will eventually be passed by new generations. So while preparing for the inevitable upgrade, you don't necessarily want to shackle yourself with a lack of flexibility or options.
Anyway, thanks for the input. It definitely got me thinking in a different vein.