I've never been so insanely filthy in my whole life, including after scuba diving in a Lake Ontario algae bloom, as after riding in a drizzle w/ marathon supremes and no fenders.
I blame the lack of fenders more than the pattern on the tires, and in fact I really can't see myself running anything but schwalbes when available. I do wonder what fenders you've rejected, something like PB Cascadias w/ a decent mudflap do an amazing job of keeping the road spray and grime off you, no matter how wet you might be getting from above.