Okay, enablers. I was looking at cyclocross bikes for hauling a kid trailer, because I want something that can do gravel and pavement, but the guys at the bike shop just about talked me into an Aurora instead (with a few modifications for my purposes). I have to order it, though, because they don't have it in stock.
They'll talk to me about fit but I wanted to see what you all think. I
think the 50cm is right for me -- specs are
here. The effective top tube length is listed as 535, which seems pretty long, though. I seem to remember that there is something about the seat tube angle changing how that reach is going to work but I can't get my head around it.
For comparison, my road bike is a 53cm, and I believe it had the same effective top tube length, and we had to put a 5cm stem on it to make it fit me. I'm 5'6 with longish legs and a shortish torso.