Pork Barrel questions re: Depth knob value and alternate op amps?

[mgwhit]

I finished my Pork Barrel board last night, and after one false start (never put a voltage sag knob on your test rig unless it has a detente at one end or a built in switch) got it up and running and sounding pretty good.  I used the 3007 chip, so I tested it at both 9V and 12V.  I've got a Road Rage on a rotary switch on my test rig, so I can go back and forth very easily, and I think 12V sounds noticeably better. 

However, I think the buffered/blended signal sounds a little, dare I say it, midrangey.  Could this be the 4558?  Could this be my brain?  Has anyone tried alternate op amps for IC1? Any recommendations?  I've got some 4580DD's, TL072's, LM833N and NE5532P's laying around I could try, but only so much willpower.

Also, I measured my B100K pots before I soldered them on, and one of them was 99K, but the other was 91K.    I looked at the schematic and it looks like both of them are just being used as voltage dividers, so I figured it might be okay as long as the value was close enough and the taper was truly linear.  I went ahead and soldered it in as my Depth pot since I'm planning to do the Depth-increasing LFO LED mod anyway (R39 socketed).  Is that value affecting my maximum (or minimum) Depth?

[mgwhit]

I went ahead and subbed in a 4580DD, which I had heard described as low-noise and more transparent than a 4558.  I thought it cleared up the middiness I was hearing and added a bit of sparkle.  Maybe a tiny bit of volume, too.  Might be psychoacoustic, but I'm going to leave it in for the time being and save my 4558s for overdrives.