I don't have my TimeFactor in front of me to verify this, but I'm pretty sure that the Vintage Delay does have the kind of time-pitch relationship you are looking for, whereas the Digital Delay drops samples to fit the new time length.
also, smoother transitions in the delay times happen when slowly sweeping the knob, and you can get millisecond accuracy by:
1. turn the knob for the parameter you wish to micro-adjust
2. tap the tempo footswitch
3. turn the encoder (the fx selector knob) to make millisecond adjustments.