i am both a sling and bipod fan - if you are going to buy a bipod, harris is good for the money, the only complaint i have is that there are no measurements on the legs - (i would prefer ruler style on a side so you can have both legs set to a fairly exact length. They might have added that to them, i have no idea.
Slings are awesome, depends on the rifle. My bolt action has a bipod and a 1in, leather, old school military sling and my M1A SPR has a bipod with the same MIL carry sling as my bolt and my M4 has no bipod and a single-point silent-clasp nylon sling. I use the bipods(all of them are Harris Model L Standar Series 9-13in version) when ill be on the ground for a long time, and the slings when im in motion.
There are three versions of the Harris you can buy(i just checked around) - The standard(the one i own) has no leg increments and does not swivel. The M Series has Leg Notches but does not swivel. And finally the S series has the swivel but no leg notches.
I would suggest an S series because the swivel is nice to have once you plant those two legs in the dirt.
my .52(that post ended up being a whole hell of a lot longer than i had wanted it to be, sorry)
AA