The OD-20 is totally awesome.

I have a "Q" crybaby going into a tremolo to super-phase shifter, to a DD6, to the OD20 going into the Marshall and it is totally cool.

I have the 4 memory presets getting heavier from the tube screamer (for southern rock) on manual to turbo-metal-meltdown in memory bank 4.

If you like a lot of different distortion / overdrive stomp boxes, this is the Mac Daddy !

I think they come in at about 150 usd new however with it being Boss id have no trouble getting a second hand one. it is also very easy to operate and program.