I've used em all...
I had the first generation of camelbak waist packs. Pretty bulky. The new ones are much better, but I have a cranky lower back, and it hates the weight tugging at it. I have enough weight w/ my gut!
I also have a fuelbelt. I like it, but sometimes the bottles are a pain to get back in the elastic holder thingys.
I'm thinking the amphod looks like it would work swell.
So knowing me, the queen of the gadgets, I'll get one soon for IMAZ training..