Welcome, Cowtown!
Check your email for my response.
I didn't touch on a couple of things in the email that I've now thought of, so I'll address them here instead of stalking your inbox.
With as comfortable as 3 wheels makes you, as far as engine size the 990 Rotex is good.
What kind of riding are you thinking of doing? There are two different models, the RT which is the touring model, with all the bells and whistles for comfort and ease on long rides, and the RS, which is the sportier model. For my interests, the RS is perfect - around town, shorter distance rides (a couple or three hours one way is usually as far as we tend to go) and I like the sportier look. The price tag is going to vary widely, as well, depending on which model interests you.
I would highly suggest taking a test ride before you buy, to at least give you a feel for it. Having said that, it'll still take you a couple or few hundred miles to get the swing of it and be comfortable in the saddle, because it is so different, though your experience on an ATV will certainly cut that time considerably.
Fire away with any questions you can think of, and we'll be happy to talk to you about them!!!