I have a 7-footer for my DK45 and haven't had any problems with power or traction using R4s; I don't know if traction would be an issue with turfs, but power would be fine. Width can be an issue in some situations, but it's nice to completely cover the tire tracks. FWIW, I have a bracket welded on mine to hold a length of RR rail for extra weight. Now I wish I had T&T...that would be REALLY handy with the box blade; hydraulic rippers would be icing on the cake (but that's not going to happen)!
BOB