I am "petite" (5'1") and recently acquired a Surly LHT 42 cm. My road bike is 44cm (Specialized Ruby) and I had to change out the bars and seatpost to improve the fit, and I still feel like it doesn't fit quite as well as Ruby. Maybe there is a little more tweaking I can do but haven't had time to get with the fitter again. I have used it for one overnight camping trip and for a few grocery store runs. I haven't ridden a cross bike, so I can't speak to that, but I think it would be okay on some light dirt roads.
It feels stable with the load once I am riding- even if it is awkwardly heavy before I get moving. It's definitely a much heavier bike to start with but it's not that noticeable while riding.
Hope that helps.