I have a Xerograph Deluxe with an expression pedal. I love this pedal for the synthy, growly envelope it has. I really does that sound so well. However, it does not do so well with that funky, vocal type of wah sound IMO. I am looking at getting something with that type of sound. I have a wonderlove on order from prymaxevintage. I would also like to try out the new version of the proton, but those are out of stock. What do you know about the differences between the two? What other filters should I check out?