I have an option of buying direct or through a dealer. The dealer is an hour north, Co-motion is an hour south. But I don't get the impression that it matters, the ability to upgrade the Speedster does not appear to be an option relative to fork, wheels, timing belt - they direct you to the Carrera if you want to do that. Or I would lose the cost benefits of buying a package.
I knew the wheels would be the most contentious issue and it is for myself as well. My inclination was to go with the Carrera, run the Rolfs and if I have problems, purchase a set of more durable wheels. Co-motion and Rolf both insist that their wheels are meant for tandem use and yes, you might see some shorter life as you do with most performance upgrades. Also, some unknown percentage of users have experienced problems with Rolfs. There is probably an optimum wheelset that can be built between the Rolfs and the Speedster wheels. When I upgraded my road bike after 20 years, I truly believe the wheels were the biggest improvement I got.
I prefer the carbon fork, neutral on the timing belt and torn on the wheels.

My original question is really would one expect to notice a difference between the two bikes or is the difference so small, it's lost in the noise and one's perception? Why did the Carrera feel more lively?

Thanks for all the responses, they help.