A buddy of mine started out on the XB12ss. I took it for a spin a few times & although definitely wheelie prone if you're tempted to do so, I wouldn't say it's a BAD bike for beginners... there are certainly WORSE bikes to start out on.
The 9 is definitely a much milder powerplant though. Never ridden one but after riding the 12, I wouldn't necessarily dissuede a new rider from getting the 9 should they express interest in picking one up...
If you want to do more research on the Buells, hit up
www.badweatherbikers.com/
It's not really "spoken" of much, but Eric Buell himself is a frequent visitor on there under an inconspicuous surname.