Fender Mender - very cool distortion gadget

I picked up a Fender Mender off FleeceBay the other day.  For $30, it's a very cool distortion device. 

If you aren't familiar with it, it's a plug-in module that connects to the normal channel V1 & V2 tube sockets.  Once the module is plugged in, you plug the tubes into sockets on the module and connect the ground cable.  Basically, it's a non-invasive way to change the gain of the preamp. 

I haven't played with it much but it really makes my BFSR cook.  It goes from mild to wild (almost Fuzz like) by adjusting the onboard gain control.  Add a footswitch and you can switch between the std. Fender clean on the effects channel and a boosted or high gain tone on the normal channel.  Also, it enables reverb and tremolo on both channels.

The only quirk is that you have to plug in to the effects channel because the normal channel input jacks are disabled.  I'm curious to hear what it sounds like on my '70 Marshall.

Anyone else tried one of these?