The only time your power is reduced without rolling back the throttle is when the bike attempts to save your hide because you're being overly agressive ryding the roadster.
It's the Vehicle Stability System (VSS) that will cut engine rpm's to do what it can to keep all three wheels on the ground and the rider safe. It's a feature and a darn good one because riders can become overly confident far too fast on these Spyders.
Without the VSS, the Spyder would not exist. I early development (pre-VSS) the Spyder program was nearly canceled because of stability issues.
The VSS is way smarter then the driver..... it uses inputs from an accelerometer, the brake abs sensors, and engine inputs. It knows when wheels are spinning when they shouldn't and when the center of gravity is going somewhere you don't want it to go.
The vss stuff is a pain. I have not disabled mine, but I have raised the threshold at which it kicks in WAY higher by replacing the entire suspension. About 40 or so percent of this can be accomplished by just replacing the sway bay.
I know this is a late post for you question. Perhaps you have already bought a spyder or have decided not to get one.
I have 1 significant piece of advice; If you intend to buy a new bike, make sure that all recall work has been accomplished. I bought a 2010 RT Se5 about 3 months ago. It came with clutch & steering problems. The rear shock also leaks. The place I bought it from is working on repairing it all but in the meantime I can't ride the bike much. BRP initiated aclutch recall before I bought the bike . I guess the dealer did not know about it. I am looking forward to having a well running bike.
Good Luck, ed mcmillan
I'm probably just too old and cautious ... but ask just about anybody who has a conventional VSS-less trike what it feels like to "bicycle" it , and I'm sure that you'll be happy to enjoy the technology...
The front swaybar swap does sound like an easy way to reduce the dreaded bodyroll in the twisties; that change alone helps keeps the VSS happier...