Sightron S-Tac 4-20x50 FFP, any pertinent experience?

The S-Tac is a great scope with one of the best reticles (MOA-2). I had one one my TX200, but replaced it. They are so long that they overlap the loading port making it hard to load. That started my quest for a compact scope. Search for my post on my review. I finally settled on a GPO 4-16, but an Optisan CP 4-16 will work as well. Now, there’s nothing covering the loading port making life much easier.
 
I’m looking at upgrading my Hawke 4-16x50 Airmax to a Sightron S-Tac 4-20x50 FFP scope to use primarily for HFT With my TX200 HC. I suspect that the additional magnification along with a larger scope wheel will help in getting more accurate target distance measurements. Does anyone have any experience with this scope they can share? What kind of scope wheel has been used with this scope? Was the scope wheel fitted to accommodate the scope illumination knob?
In my experience calibrating yardage at one magnification and shooting at a different magnification is a problem. Yardage estimates aren't repeatable. I have an S-Tac 4-20x50 FFT and just had Eric Sanders make a nautilus for it. Works very well and his work is exellent.