Did you use a bowden tube on your delta-pi? I have a scannermashup repstrap with a bowden tube and it works very well.
I only had to calibrate the right amount of filament retract and set a fast retract speed.
I'd recommend using a bowden tube on a delta for sure, but both setups will work.
If you used a direct drive right on the end effector the weight being moved around on a delta head it would slow your printing speeds quite a bit and cause more wear on your delta rod connections.
EDIT: Also, do you plan on using a stepper motor with a gear box? I ask because 3mm filament directly driven by a stepper motor doesn't work very well.
I only had to calibrate the right amount of filament retract and set a fast retract speed.
I'd recommend using a bowden tube on a delta for sure, but both setups will work.
If you used a direct drive right on the end effector the weight being moved around on a delta head it would slow your printing speeds quite a bit and cause more wear on your delta rod connections.
EDIT: Also, do you plan on using a stepper motor with a gear box? I ask because 3mm filament directly driven by a stepper motor doesn't work very well.