I don't believe the trans problems posted are as wide spread as it looks on some of the forums.
Speaking as a former TBS owner, you should transition smoothly to the Rocket from the Adventurer. Similar sporty handling, with MUCH more POWER!..
If Triumph had built a 1500cc crusier, I probably would have went with it over the Rocket. But now that I've had the Rocket for 15,000 miles, I am more than happy with it and am glad the smaller option was not available at the time..
It's a typical Triumph. At first, shifting is clunky, there are rattles, etc. But, after about 10,000 miles, just as my TBS did, everything just smooths out. The transmission shifts smoother, motor runs smoother, gas mileage improves, etc.
If you're lookng for a larger bike that capable of thrilling acceleration as well as comfortable touring, you can't beat the Rocket..