thermodynamically, as the pipe is an energy-recovery device, using exhaust gas heat to supercharge the intake, you could see some improvement in efficiency from wrapping the pipe. on the other hand, you would be increasing the temp of the cylinder gasses in the compression stroke, thereby increasing your chance for pre-ignition, which would lower your power output. The heat wrap should slow down the sonic waves in an incompressable exhaust gas medium, by increasing temp the sound waves slow, but the pressure inside the pipe would increase from the temp increase, making the exhaust gasses denser and therfore acting as a tighter 'spring', decreasing response time and raising your powerband. Usually pipes are calculated as adiabatic, as in, no heat transfer through the walls of the pipe, so heat wrap might get a pipe closer to its intended design, but the level of modeling complexity makes this very difficult to do. I would say it is certainly worth experimenting with, but it could go either way depending on the exact pipe itself, even something as insignificant as the thickness of the metal the pipe is made out of, could cause it to switch directions in terms of which way the powerband shifts.
also, on daily driven bikes, heat wrap holds moisture against the bare metal of the pipe and will rust pipes out in a couple weeks, no shit, i've seen it happen with RD yammies.