I don't mind it at all. It's actually a lot cleaner than I thought it would be. In a pinch I would even use it as my clean channel. It doesn't come close to the AFD mode...that channel is awesome!
To answer your question...I'm don't think Slash does use it. From what I understand he runs this amp on AFD and still uses his old silver jub for cleans.
this guy does...
YouTube - Marshall AFD 100 demo SLASH sound clip
see the description and comments....
It does sound too thin by itself. But it sounds perfect in the mix, with a band, etc.
I am learning to like it, it's thin but has the clarity. Ain't too bad after spending some time tweaking the eq.
I'm using a 2X12 1936 Vintage cab with a R8 & R9.
I just saw a new AFD100 demo uploaded yesterday. Can't wait for the YJM100 as well.
YouTube - Marshall AFD100 Slash Signature Head demo