First of all, where do you shop for gear, Dr_Simon? Because the shop I go to (Long & McQuade in Canada) lets me try out my gear for 30 days, and I can return it, no questions asked, as long as it's in decent condition. And I've bought several effects from them and ended up returning them (e.g. Boss DD-5, Dunlop JH-1, Boss GT-3, Boss GT-6) when I discovered that either I didn't like them or that they were too much money for what use I got out of them.

Secondly, re: the GT-6 - the wah modelling is alright, but obviously not dead-on accurate. The GT-3 wah really sucked, and the GT-6 improves on the GT-3. I found, though, that the GT-6 was waaay too complicated for me to use, and I have pretty good experience with computers/programming equipment. The parameters weren't well explained, and I didn't have a year to fool around with it and master it.

I've since decided to totally simplify my rig, and soon my rig will consist simply of guitar->Dunlop 535Q wah->delay->distortion->compressor->EQ->amp. (effects are in no particular order).

I found that it was such a pain to change settings around in the GT-6, even with it's increased number of knobs and buttons (as opposed to having to change settings via menus and scroll wheels). That is what really pushed me towards simplifying my rig with stompboxes of effects that I really use.