I have owned quite a few large frame Smith's, including a couple recent models. I would pick the 27-7. The pinned barrel, and counter-sunk chambers of the 27-2 really mean nothing as to performance and reliability. My experience with the newer Smith's is that they seem to be more accurate and better machined then the 27 / 29 dash 2 guns. Some don't like the MIM hammer and trigger used on the newer guns, but I note in the picture that the 27-7 gun in question is a PC gun, and uses the case hardened parts. Also, the 27-7 should be covered with Smith's life time warranty. Now if you are more into collecting classic S&W's, then the 27-2 would be the obvious choice. They both are nice guns.
Larry