When I started learning how to ride, everyone recommended starting with a 600. They pointed towards a few older bikes, like the CBR600F2, which wasn't very powerful, but had a very nice upright feel. I was really scared to ride on the street, but my dream of racing motorcycles overpowered my fear in a lot of ways. I think finding a goal and pushing for the goal are very important things. If you just go out there and ride, sometimes you won't really progress well. However, if you have a goal and work towards it, then things are learned much quicker and if you fall off the horse, it's a lot easier to get right back on again.
I spent about half a year on the CBR, racked up around 18k miles doing some longer distance rides, before getting my first Ducati, a 2001 748S.
What makes sportbikes harder to ride is mostly the body position. With upright machines, the body is in a central position, with feet below butt and arms extended straight out to handle bars. This gives the operator much more control of balance and control of the machine. The moment you put your feet back and start arching your back over the bars, you start to make that balance a bit more difficult to achieve at slower speeds. For slower people, this is a big deal because balance is everything when you're going really slow.
The older Ducati superbikes can be more tricky to ride for a beginner due to the clutch engagement which can be harsh at times and of course the power delivery can surge with throttle input on those machines as well. It takes some time to get use to, but it could absolutely can freak beginners out. The newer bikes are a lot smoother, especially the wet clutch one's like the 848, they're in a different league smoothness wise.
Since my Ducati Superbike experiences, I've tried many other bikes and found one that I will mention. KTM has done a great job with the Duke lineup of machines, especially the Duke 690. It's a stellar beginner bike, not only because stock it has a lot of very cool safety features, but it's easy to ride AND most importantly, you can add crash protection through their parts catalog for peanuts. So you can deck out the bike with the crash bars for not much money. Plus, they're great on gas, pretty light weight (321lb dry) and not too expensive. If you can find them used, I've seen them go around $6k, which is a steal for what you get. I only sold mine because it was older and I wasn't in love with the older motor. KTM has since done some minor changes which appear to fixed the problems, which is nice.
I'm a SCUBA instructor. I was teaching a 12 year old girl how to dive. It was her very first time underwater.
Small world, me too! I'll PM you when I'm back in town mid July.