I own an SXT, Nitro and Zipstick.
The Nitro is narrower in the grip area than the SXT, and the Zipstick seems to be between the two in width. Most of the Zipper grips would probably be called medium, not overly deep, and are very natural feeling in hand with minor finger grooving on the back.
The grip on the Zipstick is second to none in my hands! I think that the main difference is the width and small cut on the right back side of the shelf, which lets my thumb ride higher.
Also, the Nitro riser is a good bit sleeker and lighter than the SXT, but some people like more riser weight.
Don't own an A&H to compare.