I don't own a Surly, but I know enough about steel bikes to address some of your questions. The bikes you mentioned are, indeed, on the heavy side, but they offer the signature smooth ride of steel. They can take a fair amount of abuse.

What kind of riding do you plan to do with the bike and on what surfaces? Do you have a lot of hills to contend with? Do you plan to do any touring? Have you considered any other manufacturers?