Pay the extra $6 and get a Scattergun ext.
I've used both Choate and Scattergun extentions. I think the Scattergun is superior by far. The Choate may work, but it seems flimsy to me. The Scattergun is "beefy" to say the least.
I've looked at the Vang Comp extention, and while I like the guys at Vang Comp personally, I can't see paying twice the money for virtually the same extention as the Scattergun.
Also I like the Scattergun's follower, the "nipple" allows you to readily feel the follower, to confirm the magazine is empty. Also the green is a lot easier to see than the orange when checking at night.
Just my opinion and it's worth every penny you've paid.