I'll NEVER understand the criticism of the virtual cadence feature of the FlightDeck.
I KNOW if I'm not pedalling, just coasting, that the cadence it gives me isn't "real" - duh. OTOH, it DOES tell me what cadence I HAVE to be pumping at in order to be "under load" - so I find that useful, not "****", when kicking back in from coasting.
I use the cadence, avg speed, max speed, distance, and trip time ALL the time. Plus it keeps cumulative miles, provides a clock, and the gear readout when you shift is pretty cool, too. So it does everything I'd want it to, wirelessly.
I use an HRM and I've yet to have any interference problems with the FlightDeck.