How great that this has come up again just now, i've literally just gotten home from work, 13km one way in the pouring rain. It's the first time i got to test out my 45mm SKS Fenders, they did really well considering.
I did ride home once a month ago on wet roads with the 1/2 fenders, i got drenched from all the spray, the bike was a mess, not very effective, i had mud on my chest where it wouldnt' normally be with no fenders at all?
Very wet drive train with road gunk and mud over it.
Today however was much nicer, to be honest i still got a bet wet on my legs and shoes, but just wet, not soaking wet, and was nice not to have the spray in my face and down my @r$e crack either!
The B17 was well protected from underneath too with only a minimal amount of moisture from the 1/2 hr ride home.