David,
I ended up with a River Anchor like
this and I believe I purchased the fifteen pound model.
I like the link you posted although my only concern would be the anchor hanging up on debris and not being able to pull it up.
I will say that I have been able to keep my boat in place under flow with the 15lber, but that anchor is struggling to do that and if it doesn't get a good grip on the bottom.
Steve