As I have said in the past I love my Disc Trucker and as someone with a little more to love and a chronic overpacking problem. I haven't had any problems (aside from the overpacking). It is a comfortable ride that can handle my weight and my gear. I would get some ergo bars (with a good wrap such as Fizik 3mm thick tape) and a seat change but I think it will handle everything. You might want to get some handbuilt wheels with a higher spoke count but (while knocking on wood) I have yet to break a spoke on the stock wheelset.

I don't have a harsh ride on any of my steel bikes the only harsh ride is my fixed gear commuter and that is aluminum and it isn't too bad but I when money comes I might get a steel frame.