Sliding.
I think that sliding has to be the way to go. You minimising your risk of injury and you are able to shoot efficently at the same time.
If you are sliding and you need to have a low profile, skid onto your knees and then drop to your hip on one side.
At a game I was at recently I slid on my knees behind a car, but I slid too far and ended up in the open, but because my gun was up I shot a guy, and scrambled back in. Anyway, I think sliding is better.