Those three are in the same pricerange, have similar footprint, similar features. From the YT demos I like Mini Vent most, it also looks the coolest of all free for me. Is there any reason I should consider getting one of the other two and forget about the Mini Vent? I can't afford anything more expensive than these, but maybe I'm missing some pedals? It must have stereo out (mono input is fine), and slow/fast speed with graceful acceleration, switchable via footswitch. The more it nails Pink Floyd and Cream's Badge the better.