Since you even looked at the TTS superchargers, this is probably a lot about performance.
If you like the looks of the Rocket 3 Touring better, you don't need to worry. The engine is the same as the Roadster, and it is really easy to tune it to have similar horsepower.
The VTX 1800 has about 85 rear wheel hp stock, if I remember correctly.
In original state the Touring has about 95 hp and the Roadster 120 hp at the back wheel.
Just adding a good filter, full aftermarket exhaust and Dyno tune will give you around 160 hp at the back wheel on all Rocket models.
You don't even need a blower to exceed 200hp ... you could choose to go for a R3T with a 240 rwhp Carpenter kit!
So the engine is not a problem - but if you go for topspeed runs, it should be mentioned that most Tourings tend to weave over 110mph. I have a Roadster and have just mounted a smaller windshield, to be able to go faster than 125 mph without fear.