We have had all hte dicussions and 'arguments' here in the UK before the class rules were decided. Comparing the choices against the then-standard 4.cell/20T motor, the 1S/13.5 came out as being the closest in feel and speed so that's what we settled on.
At the beginning we had a 2S/21.5 class, but that has been dropped by racers who went for the 1S/13.5 option in numbers. We have taken that class out of our rules and just one or two clubs continue to run it. It worked while there were few 1S speedos and new drivers didn't need the hassle of a voltage booster, but now there are lots of 1S speedos around it isn't needed.
These cars are sensitive to weight. run them too light (below about 920g) and they are difficult to drive; over 1000g and they lurch around like they are drunk!
The car's potential is limited by the rules - no camber change on the front axle, solid rear axle only, thin tyres and high bodies. Anything above 13.5 makes them difficult to drive.
17.5 1S is a good call. We have put that in the BRCA rules as our new ProductionCup in the hope that it will give new drivers something competitive to drive, yet easy on the skills and the wallet in their early days learning to drive. I haven't driven one, but I imagine it would end up as a cheaper version for USVTA with all the fun of the racing and less of the costs of the crashing!
I hope you all have fun with the class. I am not sure how well it will take off in the US, but I hope you have a lot of fun trying. Good luck!