I have heard from several folks that one advantage of subspecialty is that you see cases with experts in that area, so that the teaching can be better and more focused. You also will probably spend less time taking the case to a subspecialty consultant when the original attending asks you to. For the attendings who do it, they might be limiting their future career mobility because unless you are a nationally known expert, most jobs involve signing out more than just one area. For residents, that's less of an issue since you rotate through areas. I think one advantage of the generalist sign out model is that it is easier to find attending coverage. If the volume is not high, the GI pathologist on subspecialty signout might get crushed with volume while the soft tissue person has 5 cases.
I haven't decided which I prefer yet. I think for residents both are pretty effective for various reasons, so I personally am not going to let this be a major factor in my decision. I am still debating merits of program size and reputation vs other intangible factors.