traildog – I got a small TCX which feels similar(ish) to a medium OCR road bike.
The bottom bracket height and tyres make the TT higher, so at 5'8" with a 29" inside leg I am happy with a small, length wise it feels good too. You get plenty of spacers under the stem so you can tinker with the height at the front quite a lot. It's a compact frame so you get quite a bit of seat post visible, but not silly amounts.
I asked my LBS in Urmston to order one in for me to look at, they also matched the price that I had seen online of £600. Can't fault it for the price really.