First, I would like to know if there are different versions, sizes (other than 1" or 30mm), or models of the SPR mount?  Someone had for sale a LaRue SPR 1.93 (or 1.92, I can't remember).  I'm just wondering if the number has some sort of meaning?

Also, does someone have a quantiative measurement of how much higher the LaRue Aimpoint mount is in relation to a standard Aimpoint mount such as the ARMS 22m68 with the full or cantiliver spacer?

The reason I ask is I'm looking to mount an Aimpoint 3x mag on the Aimpont twist mount.  I currently have an ARMS 22m68 with the cantiliver spacer and know that the the two will line up.  But, I was thinking of upgrading to the the LaRue Cantiliver mount which will make the twist mount too short.  However, I can't see why you couldn't double up on the Aimpoint twist mount spacer.  Unless it's too thick.