Same signals applied to my 20 year old LeCroy waveblunder 64Xi. Gigawave 6GHz, 1TS,12-bit vs the LeCroy's 600MHz, 5GS, 8-bit. Of course, the LeCroy has a faster sweep rate (<sec vs several minutes), but the transitions are also much more discernible. Of course, the 64xi can't show 35ps transitions like the 6400 can.
***
Right tool for the job. If you need to measure fast edge, 2-state signals, 6400 really shines.
***
Qualify that with MHz trigger rates....