I think there are more complaints about the hotplate than there should be. First off you will lose tone if you attenuate over -8db, mostly due to the fact that there is a loss in speaker movement.
You should hardly notice, if at all, when you attenuate at -8 or -4db and have your channel masters around 12:00 and output at 12:00.
When I attenuate my RKII at -16db or greater is starts to sound like my Vox Solid State/Tube Hybrid Modeling Amp. You just aren't moving enough air!!! Kinda like listening to music on headphones.
Trust me the people who designed this thing I'm sure looked at the signal on a spectrum analyzer and then tweeked it till it looked the same(other than an even loss of amplitude per frequency component), when no attenuatuation was done.
I think its great for on stage volume control. It probably isn't going to sound that good for playing at home in the bedroom.