I have to give a
big +1 to the MXR M82 Bass Envelope Filter idea. I just picked one up after a fairly long search for a pedalboard-based Filter unit, as my SWR Mini Mo' "Bassynth" Envelope Filter-and-then-some effect has been one of the high-water marks to my ears and I was looking to find a reasonably priced pedal
(under $200, I couldn't justify more without a steady current gig) that could approximate its tone... and yes, I somewhat regret selling my Deep Impact, even though it and my Bass Whammy funded the majority of my beloved Mini Mo'. I'd argue circular reasoning, that I didn't think I'd be going back to pedals or at least pedals that the Mo had covered, but my desire for a "B-Rig"/Secondary Preamp and thus a decently-equipped pedalboard made that a moot point.
Check out these two great videos that I believe really show off the positives of the M82 -
Bryan Beller of Dethklok, Steve Vai, & Mike Keneally and
Uriah Duffy of Whitesnake, Toni Tony Tone, & Lyrics Born. Two great players with
very different styles but still sound amazing through the MXR!