Blues Breaker questions

[GibsonGM]

Hey,
Built a nice Blues Breaker, used a green LED, and a 1N914+Ge diode for clipping.  It really rocks.  I lowered the R's going to the diodes for more gain, which worked well, and used a 1M pot for the drive rather than 100K.   

1)   My issue is that in the last 5 to 10% or so of rotation, increasing the drive, the bass really jumps up a lot.  Seems to happen where the pot measures 1.5K from output side to wiper.  I'm thinking this is because I am lowering the resistance between the end of the pot and the wiper....so, maybe trying a fixed resistor off the wiper might solve this issue?  Or should I just put it in series with the pot, on the opamp input side (rather than the output side)?
The other thing that comes to mind is that rolloff cap in the feedback loop - could this be the issue?  Just seeing if anyone else has had this experience.
2)  When I roll back my guitar volume, the thing sounds like a vintage fuzz face, as if I've lowered the input impedance or something - any thoughts?  I'd almost keep it this way, and use it in place of a FF, LOL.

Anyway, the thing rocks and I really like it, I'd recommend it to anyone looking for something a little bigger than a TS but not quite 'death metal' or anything....