I like the manual better, it has a human feel to it...the auto is too perfect in the movements. sometimes that perfection can be a cool effect but usually the machine precision detracts from the groove when I hear it.
I'm going back to a Robotalk2 from a manual wah. Both have merits, but I prefer to control the wah with my attack as opposed to my foot. The Robotalk is great having two channels and a blend knob, and I find it a lot less fussy live than my old Proton.
Um, hell if I know. I would think it's the same as a filter since you open up the wah tone with a harder attack. I set one side of the Robotalk for typical soul kind of rhythm stuff and the other for more of a cocked wah kind of tone that only opens up with aggressive picking. You can also get some almost phaser kind of to tones running both sides together - the PGS and Mike Herman's clips together will give you a good idea what it can do.