not entirely true dave.baseball slides are pointless in most cases!
if running at an angle, hip slide.
if running straight - superman.
IE:
running to corner off the break = hip slide, that way when you swing your legs round your in a firing position and have no chance of popping out the wrong side of your bunker when your momentum carries you over.
running into snake = superman.
easy
If done well a baseball style slide allows you to stay gunning the whole time, including during the slide.
Much like a hip slide you can then use your momentum to kick yourself up and back onto your feet.
This is done by jamming the heel studs of your leading foot into the ground and using your momentum, along with your (folded) trailing leg to kick you up and onto your feet.
While this does have the benefit of allowing you to continue firing for the entirety of the run and slide it does however have a much larger profile than a hipslide.
So I tend to alternate between the two appropriately based on how much paint i need to dodge
Signed
Your hero
Jack