I've used both the TNC and the H-9. The TNC is a far superior product but you do pay for the difference. As in anything else, quality still comes at a higher price.

An odd note about using the standard Hall sensor for rpm readings. I have an Eagle Tree system with most of the whistles and bells. The instructions note that when all the other conditions are right you can use the hub magnet foir the Hall sensor for the unit's rpm impulse. You have to use a separate pick up sensor though. If you try to wye off the hall sensor and disconnect the power lead from the leg of the wye going to the telemetry transmitter you short out the ignition. The reason for disconnecting the power wire is because you don't want two power sources to the telemetry unit. Using the ignition battery via the power wire to power the unit means you get telemetry only when the ignition triggers.

Bottom line is you will flip that prop from here to Chrsitmas and the engine won't start until you unplug that rpm lead from the ignition hall sensor.