The Proton is a much newer box than the Electro-Harmonix designs. While it's cool and all that Mike got involved with E-H, that doesn't really mean anything in terms of the Proton. Of course he's going to say that the Q-tron is the best, but times have changed. A lot of technology has hit the street since the Q-tron came out. I have Spencer's Groove Regulator 2, and it's a great pedal. I gather it's based on the Lovetone Meatball, but I haven't used one of those. Having attack and release options is very cool.
I think it's really worth it to check out these things for yourself. I'm not saying the Proton is going to be the best, but things like envelope filters are so dependent on the rest of the system that relying on the word of people who have an interest in the product, or anyone at all, including me, might result in missing something that would work better in a particular rig.
The one that I have that I like the best purely for sound is a Univox Funky Filter that was a reverse engineer from the original Mutron III that was licensed. However, it's got the same gain staging issues that the Mutron has, so the Groove Regulator gets more use. OTOH, the E-H BassBalls is pretty amazing, especially on fretless bass. It does an awesome gurgly slower filter sound.
Of course, I should also say that I have nothing but respect for Mike Beigel's work. He's one of the great ones.