I go someplace I don't want to bring the empeg into I can leave it at home and not have to drive in total silence.

I went the single unit way, and I'm now kinda wishing that I did it the other way, just because of this. Most of my drives are 5-10 minutes long, and I find I just don't bother (or I forget) to bring the empeg with me. What would be really cool is if there were a small insert I could plug into the sled that would let me listen to the very last station I tuned the tuner module into. Then I could leave that plugged in when I bring the empeg in the house.