Re: Shooting from a bench/prone
I used the 6-9" for years, both prone and from the bench. I tend to shoot with a fairly low position in prone when I can, so it worked well.
Lately, the practical/tactical matches around here have been mixing things up and going with more varied firing points - definitely not flat and level, thats for damn sure. Several of them either put you facing down hill, shooting slightly uphill to boot, or in grass/weeds/brush just tall enough that a 'low' bipod ain't gonna cut it.
It's taken some work to get used to the 9-13", and I'm still not able to shoot quite as small of groups off of it as I can the 6-9" on a flat & level surface... but at least I can *make* the other shots, which I couldn't before.
Definitely get the notched legs and swivel head plus a lock lever ala Pod-Loc - you'll be glad you did.