Hi mountain cur,
There are no differences in the 2011 / 2012 models. Most likely what you're seeing is the fact that i have my scope mounted on top of an HHA Optimizer Speed Dial, so my scope is actually sitting on top of the Weaver Rail that is part of the Optimizer unit. This provides enough surface to hold any scope and yet it mounts on top of the PSE TAC15
/ 15i upper Weaver Rail in the center of the rail. This allows one to easily remove the recommended 2.75" from the PSE Weaver Rail.
The clearance problem that i outlined in the article was not when the cable and arrow are seated in the full draw groove. It is when you are in the process of cranking your arrow to the full draw position or once you pull the trigger and your arrow comes up and out of the groove. As the crossbow fires, it pops up and out of the groove. This causes the vanes to make contact with the under side of the Weaver Rail as the cable launches the arrow forward. Like it or not, this is a disruption and not a smooth launch process. Sometimes your arrow may recover from this contact and still hit close to where you're aiming on a target, but all it takes is one in four shots for your arrow not to recover fully.
Since all this takes place faster than the human eye can see, you can't tell when this is responsible for your arrow not being where it was intended to be. It causes what many people call a flier, but they have no explanation for what causes this condition and therefore have no way to correct it. Over time they have learned to except the fact that it occurs every so many shots.
I made the rail modifications to my own TAC15i quite some time ago because I have no tolerance or acceptance for even a single arrow being any place other than where my cross-hairs were sitting when I pulled the trigger. Anything less than an arrow being in the x-ring is never "Good Enough" to suit me. I also use a compact version of the Leapers / UTG Scope that is offered in the TAC15i package. My scope is only 9.5 inches in length but is still a 3 x 12 x 44 scope. It uses a shorter eye relief and takes up a little less space on the Weaver rail.
Myself and a few others that have spent countless hours tuning and perfecting these crossbows all believe that "Good Enough is the arch enemy of "Better and Best". This has always been the basis for the modifications and tuning work we've written about. It was intended to help others who share in this belief.
Each of the modifications that I've outlined are not to be taken lightly. I would not recommend making any modifications or changes until you are shooting almost same hole groups at 50 yards. This is a good indicator that your crossbow is aligned, squared and tuned well. If this is the case, then you can move forward to the more advanced work. If not, then go back and perform the other tuning steps that have been outlined until you have the basics down before making the basic accuracy problem a much more complex one.
I hope this helps you understand a bit more.