Re: how do you rate the differnt bi-pods
We use Harris's a lot but have used several other types and have stayed with the Harris. They are pretty reliable. Now that they swivel they are even easier to use in the field. The ones on your list range from too expensive to poorly made (China...) - relative to the Harris. There is one more that could go on your list called the Rugged Gear - not a bad unit. Legs telescope out then turn or spin out for fine adjustment as they are threaded.
ALso have one called the Snipe-pod which is pretty slick - longer shock-corded folding legs almost like a cross between shooting sticks and the attached Harris since it locks on the swivel stud. Have used them quite a bit, they are much lighter than the Harris, more $, lots of people prefer them and they are great when you get some experience.
My son and I use shooting sticks a lot - particularly like the Underwood's. They are super light, very quick to deploy and very steady if you practice with them. Not sure if he has a website but the address is Underwood, P.O. Box 924, Mocksville North Caroline 27028, phone 704 634-9009. They fit into a belt pouch and snap open in a second. The sticks are nearly as steady as a Harris, particularly if you only use the first section. They will let you do things that you can't with a Harris as they can be extended longer. Also made by Stoney Point - Underwoods might be tougher.