I have had both the Harris and the knock offs, they are almost the same except like mentioned above everything is just a little cheaper on the knock off. You can always modify either of them from Coretac in Missasuaga, it now has a larger attachment screw, a swivel ratchet system, a Phoenix foot adapter and feet, it's now twice as much but twice as good no joking. With that said I am currently looking for something lighter and better, I also found that buying the lesser of the two will have you going back for the other one in the end anyways. So yes I think for the extra cash it's well worth extra quality, but they do do the same thing.
About $120 at Coretac which is a fairly standard price, but they have all the other goodies.
http://www.coretacsolutions.com/products_bipod_systems.htm
Cheers,
Evan