Go with Frybrid, its the best kit on the market and it will ensure that you are at 160F before switching over, plus there is no cross contamination because of the control unit and dedicated return line to the VO tank. Most kits either loop the return or send the return back to the diesel tank.
The problem with the plantdrive is that it relies heavily on electric heat (which has its benefits in that it will get the oil up to temperature quickly, but if you have an efficient heat exchanger the switch over times will be similar when comparing a coolant based unit to electric heat).
Here is a comparison:
http://www.frybrid.com/kittest.htm
As a side note I am not sure if Plantdrive still uses Pollack valves, but they are trash I would definitely get different valves.
Also if you use PHO Plantdrive kits are NOT compatible with this type of VO. Frybrid kits will burn PHO.