I don't have any first hand experience with it but I hear it is better than
the teflon packing that I have used for years.

With the teflon, I do get a few constant drips while the shaft is turning
and it diminishes to near nothing when stopped.. Since I have a ridgid
coupling, I have to have engine/shaft alignment down to about .010" at the
coupling halves. With resilient mounts, this is difficult to maintain over
time.. I've redone my engine alignment once since I launched 18 months ago.
Seems to have settled in now. My point; when my engine shaft was out of
alignment (acutally our of plane) by about .030", I had to constantly
tighten the packing after each engine run... (of course I didn't know that I
had lost my earlier alignment until I pulled the coupling bolts and the
shaft couple raised noticiably when the spiget was disengaged.)

Everything is fine now.. Traditional drip under way and little to none when
stopped. I have a deep sump in the engine compartment so none of the leakoff
ever gets into the main bilge.

Steve
s/v Good Intentions