I'm 5'8"m and have a medium
The bike is a long one, yes, but the cockpit area seems very short to me. Certainly a lot shorter than my 16in Inbred. It's the only bike I've ever had that I don't feel the need to fit an inline seatpost as it feels short enough as it is. I guess this is due to the slack head angle kicking the wheel foreward and the bars back in relation to other bikes I've ridden.
I'd say go for a large at your height because of this, but TRY ONE FIRST!!!!
Also, I tried messing with the stem length too, and it pretty much ruined the handling. I tried a 40mm and a 50mm stem: No good at all, either of them. I went back to the OE stem which suits the bike perfectly, and fitted some slightly wider bars (710mm IIRC, so about an extra inch on each end basically)
That worked very well. Apart from that and a decent saddle, all the contact points on mine work and fit me perfectly, so no need to waste any more money on them! 🙂