5F1 amp mod question

[leevc5]

I have a 5F1 installed in a cabinet with a 40 Watt solid state and a 12" Celestion speaker for flexibility. I like the 5F1 a lot but am thinking about adding a tone control to it.

Have any of you seen this:
http://www.runoffgroove.com/tonemender.html
If so, what so you think of it? Or should I just pick up a MXR EX pedal?