I currently have two bikes equipped with Rohloff hubs. I picked up the second last week, so not a lot of time with that one. The first one has Gates Carbon Drive and I have had zero complaints or problems in well over 4k miles. I'm totally used to the noise now and it does get quieter after around 2k miles and an oil change or two.
Whoever mentioned the Hebie chainglider: I had one for a short stint before I moved over to the Gates. It is a clean option as well, just insure you open it once in a while and have a look at your chain. Just because it is "enclosed" doesn't mean water doesn't get in.
I always wanted a Rohloff bike, before owning one I had a few Alfine bikes. They kind of gave me a taste but I still wanted the daddy of all hubs.
Shawn