Jay,
I too have a TC-24D but pull the 6 footer behind mine. When I bought the whole package, the guys at the dealer couldn't even agree on which would be better for that size machine, but made the argument that I could always take a smaller bite or worst case, cut six inches off each side.
Hard digging it will stop my tractor dead in its tracks, but so will the 54" bucket on the front. I am glad I got the 6'. Snow removal, road grading (compacted gravel), and spreading crusher run gravel I have had no problems, and I pushed a lot of crusher run building my driveway. I angle it sharply for snow removal, and do not have any problems kicking sideways, but I do have chains and loaded tires. Unless you're going to be using it like a dozer to peel hard dirt, I think you will be OK with the 6'.
I have the Woods RB-72 and have been happy with it. I don't think you can go wrong either way.
Brad