I've only used the Leki Anti Shock System. Specifically their "soft anti-shock lite" system.
I'm wondering if my inability to feel any perceivable difference between my GG LT's and my older Lekis, comes down to the grip material. My lekis had cork grip handles, but were made of very hard, compacted cork, making them feel very similar to plastic. The GG poles have cork grips that feel like very very soft, like mushier wine corks...i'm wondering if those act as shock absorbers in themselves.
edit* Oh, Chris's point probably further adds to the explanation.
You can always pick up your poles from REI, and if they end up being uncomfortable because they lack an anti-shock system, you can exchange them for a pair that do have shock absorption.