Conrad-Johnson C1 Cap upgrade

Has anyone out there had the teflon cap upgrade for their CJ pre or amp and could you comment on the improvments/changes etc? I recently picked up a vintage PV-9 which is quite nice but a bit lacking in accuracy and am interested in what might be possible. It is just a great reminder of the PV5 and PV7 I owned back in the 80's and there is much to like. Certainly better than those two but the caps are getting older and it might be worth pushing the limit to see what could be gotten. One big issue for me is that the power supply in this pre is quite hefty and the premium for the upgrade isn't cheap but I'm told to consider that it would be wonderous putting it in the league of the ET5 which tells me little, haven't heard that one. I don't want to take a leap of faith without some feedback from those that have done this. Thanks in advance!