I really liked both. I remember the KSD (I tried the 70's one) playing very nicely. It had a jazz bass sound but what surprisingly powerful. I imagine it's quite similar to a marcus miller jazz. Very good neck, don't remember it being particularly heavy and would have bought one if it was a bit cheaper.
The G&L is a different animal. The neck is beefier, I find this type of neck very comfortable, but perhaps not as "quick" as a jazz neck. Not sure whether you mean the tribute versions or USA but they are nearly identical basses. See my review about the G&L.
Although the KSD was very nice it was a little overpriced, not much, just a bit.