On a RG, windshield height is VERY critical, IMO. Especially if you have a BSR. Because the windshield is further away from your face/eyes, it is much easier for the top edge to get in your line of sight when going uphill, and that drives me nuts. So you'll likely have to change windshields to find one that suits you on a RG, unless you don't mind looking through the windshield, then the choices are easier. The face of the radio is further away too, so it's a little harder to reach things if you need to, but I rarely have to do that when riding down the road. The RG "feels" like a bigger bike because of the fairing design. The RG is affected a little more by direct crosswinds than the Batwing, but less affected by headwinds or big trucks in front of you. And I do think the RG fairing design helps the bike stick to the road at higher speeds better...the Batwing is like pushing a piece of plywood into the wind when you get over a certain speed. It's not a big deal, but there is a difference. If you have a decent front end suspension under it, the RG definitely handles a little better in the twisties simply because there is no extra weight on the forks. But we're talking nuances here, not dramatic differences. Some small things: I like having the two glove boxes up high on the RG fairing...they are quite handy for your wallet, cell phone, and other small, flat items. I like the angle of the gauges, in general, but at certain times when the sun is behind you and the angle is just right, there is some glare off the gauge faces. But that's true on the Batwing too, but seems more noticeable on the RG for some reason.
Saying all that...I like the RG better. I like the "look" of the RG from the side. Since this '11 SERGU will likely be my last HD, I got exactly what I wanted, and will run it until I am either tired of it, or too old to ride. It's a keeper for me. I would have no problem with a Batwing either, if I were looking today. It really boils down to which one you like the looks of better...the differences in handling, wind control, etc. can be addressed with either bike. Personally, I think the RG looks more "aggressive" from a side view, if that makes any sense. I like the lines a little better...