I would say real life performance isn't worth the price gap, though you would get a bit more power, but even with RSTuner you can get custom maps which will take you a bit closer to an RR, plus you have the chance to custom remap it very cheaply if for instance you put cams in. It is the best value for your money IMHO.
I have had two RS, 1 182, and then a 172, I used my tuner to map them both, on both I have had custom maps and I am about to need another map for the cams. for me it has been such a deal!!! The cost of all has been the Tuner plus three custom maps.
190+75+75+75 = 415 Euros, can't imagine I much that would set me back if I have done RR sessions instead.