I'm no expert, I did sleep in a Holiday Inn once . . .
A Touring comes with most of the goodies -- which take substantial work to replicate on the Roadster. That's not to say there aren't people who enjoy the challenge, and if you're one of those, by all means go for it. You'll find a dozen years of accumulated knowledge in these pages, and I strongly recommend you do your research.
If all things are equal (and they never are), while there are substantial differences in the frame, the engines are virtually identical, and while we're here, if you are looking at either Touring or Roadster, there are no model years to avoid.
So the difference in performance you cite, is almost entirely a function of the programming in the common Engine Control Unit (ECU).
So in terms of relative effort, it is far easier to buy a Touring, that has all the goodies (though I must say, a bit problematic here in 2018, some fourteen years these remarkable machines have been produced, a Touring purchased now off the floor, would be what-you-see-is-what-you-get as for the most part the accessories for the Touring have dried up) - so Touring, with the add-ons, and remap the ECU to approach the performance of the Roadster, than the converse of buying the Roadster and going through the long, complicated exercise of adding the goodies.
Again, it totally depends on your expectations.
I totally agree with
@1olbull that the potential in the bikes lies in how they sit. Why add gel seats, bags, back rest, top box, and so on, if your heart is really into scraping the pegs ?
One substantial difference in the two models to consider is the tires are narrower on the Touring, making it a bit more comfortable for low speed handling.
One thing I will tell you, a Rocket is one of those rare items in the universe where the pleasure of wanting and anticipation is matched by the real thing when finally in your stable.