It's finally tax return season (aka bike buying season) and I'm setting aside $600-700 to put into a new fixed gear. I've had a generic frame I built up with Weinmann's and other mid-low level components that I was moderately happy with, so I want something nicer. I don't want or need to exceed 700 bucks.

To get to the point: I'm looking at the Mark V Pro's because they use Reynolds 631, but how much better is that than the IRO heat treated CroMo? I don't have any experience with IRO bikes, or any steel for that matter. IRO's build a bike website is out of the 58s at a moment - they have the Mark V in a 56. I'm 6'1" and rode a 56 with drop bars before and was quite comfortable (my TCR is a M/L 57 - I have a short torso and prefer to ride with more seatpost). It was also easy to get my weight over the bars. How do the Mark V's feel as far as reach?

What other bikes in this pricepoint should I be looking for? I'll mostly be using the bike for training in the rain, maybe a couple flat centurys and having a non-carbon bike to get around town on.