I no expert and I've never had a PC111, but my limited understanding is:
PC111 is a piggy back device that modifies what the ECU does where as Tuneboy changes the out put from the ecu at source.
Pc111 you "Bolt on" , Tuneboy requires you to get your rocket within a 1M of a PC or laptop.
Have a look at the Tuneboy website for the true comparrison.
As for which is better, many Rocket drivers here with far more experience than I are changing from PC111 to Tuneboy.
You can make your own mind up from that