I had a Hotplate for my Dual at one time, but I ended up selling it because I could dial in the same sound with the master volume. It was pointless for me to have it.
If you're looking at buying either a Single or a Dual, I recommend going with the Dual. Not only do you have the tube rectifiers along with solid state, but you can also pull two power tubes to bring it down to 50 watts.
The newer Rectos can also have the parallel loop modded to serial, if that's your thing.