[MFE III]

I used their version for a windsor, which has an even more suspect O-ring set up (kind of a pear shape to accomodate the water outlet)
Surprisingly, it hasn't leaked at all since install about 2 years ago. Even had it off and reinstalled it at least once. I used the the clear silicone (non-adhesive) goo that I use on my pool filter gasket. No other gasket or sealer. No problems so far.
Matt