It's important to not consider the fingers seperately from the rest of the left hand issues.
IMHO you should play with the fingertips both on fretted and fretless. Tips are better for accuracy and control. Variation is possible, but tips are the standard.
A second reason is that playing with the pads may lead to stretching the fingers (and not curving them), which often leads to stretching the thumb also, squeezing the hand palm, flexing the wrist, risking injuries in the long run...
http://chriskeuken.nl/health/the-nar...ist-guard.html