I wouldn't expect the Jardine header to be much different to the stock manifold in terms of heat. It's the overlaying of the pipes in the other headers that push at least one of the pipes a further couple of inches out from the engine and up against your leg that makes them so much hotter.
Your "interesting find" is not quite right, by the way. To remove cats on a Roadster you only need to replace the cans eg Jardine; or pipes such as TORs or Staintune; or 3 into 1 such as Reband, Carpenter etc. On a three pipe bike, there's only 1 cat and you can eliminate that in a number of ways - eg Triumph by-pass, Jardine system, 3 into 2 single side such as D&D or Thunderbike, any 3 into 1, or even Roadster TORs or Staintunes with any crossover.
And I have to disagree that the 2 pipe performance pipes from NewR3 look like crap. They look a hell of a lot better than the stock Roadster sized pipes (including TORs or Staintune), which are way too big in my opinion.