I'm going to go with the "not 2 small" crowd but you should try it if you can and make up your own mind.

I'm 5'10 1/2 with a 32" inseam and I have an 18" Access XCL hardtail and a 17.5" '05 Marin Rift Zone that both fit me perfectly. Once you can stand over a frame, the seat tube length is much less important for comfort than the top tube length. I'm average build and a 22.5" to 23" top tube with a 110mm or 120mm stem is about right (it really depends on how swept back the bars are).

You should try the fit caculator at zinncycles.com or competitivecyclist.com (their MTB calculator, though). Both pretty much nailed my frame size w/top tube length from the measurements I supplied.