I've heard of lots of problems with synchro DT shifters. I had a set that I think are a little different than most. These are index only but worked flawlessly for years with a chorus RD and shimano 7 speed cassette. Note the tensioner knob thing that's not present on most synchro's you'll see. I started playing around with different index rings and got these to work with a regina 6 speed freewheel and victory RD. Works better than I would have guessed. This could be an answer for DT shifting.
