Marumis are awesome. I went through a number of brands and I'm settling down to Marumi. I find them to be a bit better than Hoyas and I love that they're easier to clean. Hoyas are a b*tch to clean.
The waterproof ones are awesome, pretty much as good as the DHG ones. The DHG filters are great. I honestly couldn't tell the difference between them and B+Ws, but I find them a bit better than the Hoya Pro1D filters I had.
So far, here are my rankings in experience:
B+W = or > Marumi > Sigma (Surprise! They make fantastic filters) > Hoya = Kenko
K10/20D + DA* + Waterproof Marumi filters =
Wet them and you literally just have to shake/tilt the filter to get the water off, they bead and roll off nicely. My Olympus E-3 user friends are very happy with them.
They offer excellent value. How much are they there? I just got rid of all my larger filters and downsizing to 49mm for the DA Ltds. I get them off ebay.