I'm going to do a "before and after" comparison (PTO/VFO vs. DDS) with one of my SB-104As and one of my TR-7s using a spectrum analyzer. The DDS will be temporarily connected to the mixers instead of being permanently installed, and should IMD/phase noise figures be equal to or lower than the stock parts, every rig I own that can be converted is going to get a DDS VFO installed.
Stability, RIT, dual VFOs and split mode (without having to run an external VFO) - what's not to like?