I play in a cover band, and have to switch tones and effects often several times within a song, as well as between songs. I've been using Boss GT effects for several years (now a Boss GT-10) through a Mesa Roadster amp. I use the effects on the GT-10, but the tone is purely from the amplifier (why use digital models when I have one of the best tube tones on the market). I was interested in a number of MIDI switchers to program amp channel switching simultaneously with switching effects on the Boss GT. Not being a very techy player, I really didn't know where to start.
After a bit of research, I went with the Amp Gizmo (RJM Music Technology), mostly because it was well-rated in the few reviews I found for this kind of technology. There is a rather expensive and proprietary cable to connect the Gizmo to your amp of choice, but it will actually control any amplifier parameter you normally control with an amp footswitch. It was really easy to set up, and all I had to do was program the channel, boost, and effects settings for each channel on the GT-10 and it does everything with the push of one button.
The down side is that I lose the degree of freedom of being able to switch channels with the same effects setting. Each channel on the GT-10 has to be programmed specifically with the channel on the amplifier, so you have to plan out in advance how the banks are used in each song. I've gone from using six banks (four channels each) of effects for our usual 60-song set to 19 banks. The wiring array is pretty messy, as I use a four-cable method, plus the MIDI cable; I keep them bound with velcro straps and the tips color coded to make the system idiot-resistant.
In general, I'm quite pleased with my rig these days, but I am curious to know if anyone else out there has messed around with this kind of tech (either the Amp Gizmo or any other kind of MIDI switching/interface) and what your experience has been.