I don't think the telescoping pistons are even necessary. I mentioned before that the Tamashii both telescopes and rides up and down on the rails. But sometimes it does either one or the other. Having both is practically overkill.
Basically, I think Sideshow would be smart to forego the telescoping pistons in order to achieve a smaller piston sculpt, and just have them riding up and down in the rails. You would get the same amount of articulation. I think that's how the proto shown at SDCC was. Maybe they're planning on having the pistons telescope and that's what Alex was passing along, but from the pictures it looks like the pistons are fixed. Which would be fine.