Why be so willing to pay a premium? An EPA compliant V-Twin isn't going to be a rocket ship......It doesn't really cost the manufacturer all that much more to produce an higher output engine, after initial R&D......a head is a head, a cam is a cam, a piston is a piston, etc. Limited production would incur some higher tooling costs, but I wouldn't pay thousands for 'factory performance'.
You charge what the market will pay. On my truck, the next larger engine was the same block, mostly the same parts but was $1500 more. There is some real nice profit margin in there.
If people want that power ( And I do...) then they will be willing to pay for it at a far lower price from the factory than what they get in the after market. ie: TURBO My point is, that I don't think there is a market for a separate design of the RS/GS just based on a separate power plant. Using the same RS/GS design whether it is the one out now or the one they might make in the future is logically cost effective for BRP and the cheapest way to prove there is a market for that power.
I know many here feel the Spyder has more than enough power, and that conversation is subjective from rider to rider. To a large extent, I agree that it does. I also know that I chose the Spyder as my first Sport Tourer and that I was moving from in line 4's to a twin. The experience for me has been different on many levels... twin, 3 wheels, heavy, touring.... Although I would love to slap the turbo on it, I am constantly reminding myself that I bought it to tour.
I still want more power though.

There was something about twisting that throttle on a ZX-12R and just feeling a whole lot of grunt underneath you.
I don't feel the Spyder needs that kind of power at all, but a subtle boost of about 25 horse or so would be nice or again, the option for the base motor and a higher output motor as a premium.
After 3 years of sales I think BRP should have a pretty good handle on whether it is safe or not to put in a higher output mill. The BRP reps I've met said "No Way", that they had found more power was not safe... But those with after market top ends swapped in and turbos are proof that the spyder can be ridden safely with that power ** and that is with the nanny thinking it still has the stock 106 HP to govern.
All that said... I would cry if they came out with the option too soon as I really need to wear my current spyder out first!