I already started Low Volume Level II on a Kurt Kinetic Road Machine using my Stages Power Meter. I recently got a Wahoo Kickr and using Powermatch with it. Should i redo my FTP test?
Given that I used my power meter previously would there be much of a difference?
As long as you continue to use the same power measuring device, you do NOT need to retest.
So, if you used the Stages for power data before, and plan to continue to use the Stages for power data, there is no need to retest.
You only need to retest if you swap from one power data device to another. In your case, the PowerMatch feature will control the Kickr, based on data from the Stages, so there is nothing that should vary from a power measurement perspective.