Hey Mitch-
I have a fretless ABI, I've had it since 2002. So what specifically you wanna know? 9.5 lbs--really? mine is somewhere around 7.8-8.
Well since your already playing ABIs then this bass should be a no brainer
I'd tell you that playing the fanned fretless is no more difficult than playing a regular fretless bass, so if you feel comfortable on a regular parallel fretless, you'll feel right at home on this bass.
So first off, I played a fretted Ab1 for 1 yr before getting the fretless dingwall, and I played parallel fretless as well, so....
In all honesty, it took a bit of woodsheding and occasionally a Boss Tu-floor tuner to ensure my intonation was dead on, however i can say that you'll be able to play this bass w/in minutes of picking it up and if you have good ears and good intonation on a parallel fretless, you'll pull off 99% of your music no problem. By 2 months the fanned fretless was second nature.
I would expect the ABII fretless to sound like a ABII except w/ Mwah, and Sheldon combo of epoxy-coated wenge on the fingerboard is absolute magic. Tone wise expect everything from modern to fat. Your hand position and p'up choice should really bring out all your techniques and mwah.
Anyway I've gushed enough, I think fanned fretless is great, and as long as you know what to expect up front you'll not be in for any major surprises, HTH
frank