Works Just Like It States...
...once you have the right setting.
I actually purchased one of these quite some time ago for the same Mesa MkV head it's now being used with (via a POD HD500), but returned it 'cause instead of switching when a button was pressed, it made a grinding noise like it was stuck switching the channels. This unit did the exact same thing, however, once I read the manual's section about choosing the appropriate amp/channel type setting, it works exactly as stated and has enabled putting together quite an impressive rig. The RJM MAG and the POD HD500 in 4CM with the MkV Head offers an incredible amount of tonal options, from the head alone to the head with FX in front of the pre and in the loop, to using the modeled pre's with the MkV's poweramp. Really lovin' this setup. Thanks RJM!
More sole issue with this unit is deciding where and how to mount it. Right now - as I'm not currently playing out - it simply sits on top of the head/cab, however, I'll probably end up mounting it on a pedal board which will put it right with my only complaint about the POD HD500: bending over to make changes and save presets. That said; this waist of mine can use the exercise. hehe
Thanks again RJM and Sweetwater!