This is a great discussion that I was looking for. I will tell you my small experience but really I need more info, and this is a difficult area to understand.

I bought 2 "pedals" a Zoom A2 for my acoustic and a Zoom G2 for my electric. The A2 was a 100% success and a total asset. The G2 I am not so sure, maybe my ignorance on this effects area is keeping me from getting dialed in like I want.

The G2 has 40 presets and 40 identical preset channels that can be overwritten and altered. It is a digital processor, so tube amp guys will throw the BS flag right away as class A amplifier purists. However, at my age I cannot hear any digital artifacts (sampled at 96K) so in theory, it's ok by me. My ignorance is how to set the different areas up. You don't need a compressor, it has that stage built in...and a reverb stage, and a flange, and other effects, all in order, all with stage gains or pads, I just get lost on how to get it where I want it to be so maybe there's simply too much in one box, I don't know.