I did this upgrade to my Planar 2 yesterday. I was shocked, shocked I tell you (no, really, joke aside), that the new motor made so much difference.
All I can figure is that the rubber-band suspended motor on the Planar 2 was making micro-movements all the time. I didn't hear any flutter, not even on piano music, but something was happening. Because changing the motor made a very noticable sonic improvement in the TT.
I haven't done extensive testing yet today, but I don't think the table is running out of speed either. As I say, I felt that my Planar 2 was running just fine before the motor change too. I was very doubtful about the need for doing it.
Before I decided to do the up grade, I tried putting some foam dampening on 4- sides of the old motor to see if I could stablize it. Thinking maybe I didn't need the upgrade. But this didn't help at all, in fact it made the table run slow and it was noisey. The new motor runs very silently, and with virtually no vibration. The new motor is simply held in place with a 2 mm (aprox) thick double sided adhesive foam pad.
I think, especially with your power conditioning, that you'd be happy with improvement and feel it's well worth the $150.
Go for it.