I've ridden the ST for about 700 miles or so. It's a lot harder on my wrists, hands & shoulders that the GT is. The seating position is a lot more comfortable on the GT. Many of the ST owners have commented about the less than idyllic seating position. It does offer better wind & element protection than the ST also. However, it is not an RT. The faring is quite a bit smaller. It does present a very unique riding experience. The faring at about 50 mph or so creates a wind pocket. Your instinct would be to try to tuck deeply behind the screen, however when you lean forward just a bit, you drop into this nice body sized pocket of air. Your helmet is still up in the open air though there is not any buffeting through about 85 mph.
I was really surprised that what to me is such a small bike in stature gave such nice protection. I am fortunate to be able to ride many different bikes for extended periods of time. This is just a really pleasant little bike. It does seem to me that the company marketing does market it's similarities to the RT, but I didn't find it that way. It's a really cool bike all on its own. There may be some overlap with the RT, but it's a different bike entirely.
Just my .02