I love my Rush. I picked it up cheap and have it set up with Archetypes and 28mm Paselas and the clearance and ride are good. You may be able to squeeze 30 or 32mm tires but it's probably hit or miss. It's my 4th fixed gear and the most aggressive geometry and I like it the best.

I don't know how it would do on a trail, but it's ok on the crappy streets of New York. However the Lilac steamroller is probably more suited to your purpose.