DOD Grunge + Metal zone mid./freq. control

[ddpawel]

I would like to share some idea with you. I am planning to add mid / freq controls to DODGrunge effect. Here is a schematics:

http://img89.imageshack.us/img89/2637/dodgrungemetal.png

The problem is that Metal Zone has (in order from clipping diodes):
-output tone shaping
-inverting buffer
-low/hi controls
-mid/freq control - inverting opamp

However, Grunge
-output tone shaping
-low/hi controls

I would like to have switchable mid/freq control. On my schematics I moved inverting buffer between the low/hi and mid / freq (I would like to keep the phase).
Is this a good idea? Or maybe is there a better place for a inverting buffer?
What do you think?