I've been extremely pleased with my Falcon X50. Mine is the field target version, which supposedly doesn't focus as far out as the non-FT version but yesterday I was doing some testing for a friend who is considering this scope and found the following.......
His big concern with the FT version was that he wouldn't be able to focus on longer ranges, like 100 yard benchrest, in case he decides to use the scope for that. I was tasked with making sure he could focus on longer airgun ranges if he buys the X50 FT version. These images might be helpful to OP when looking at scope options in the same general price range as the SIII (actually a couple hundred cheaper).
First pic is with my 6x rangefinder....
Second pic is through the X50 on 50x
You can see that it gets a bit darker at 50x but the "directtv" on the dish and the small branches (guessing finger diameter) are visible right in front of the dish.
No pics, but I was able to identify a little birdy as a Junco at 122 yards that I couldn't even see without the scope. Tree bark was also clear when focused on at 122 yards.
Finally, I remember using the gun this scope is on to shoot at some paper at 100 yards a few months ago. I was able to see most of the .177 holes at 100 yards, couldn't see the ones in the thickest/darkest inked portions of target.
X50 saves you a couple ounces (I think 29 vs 32 for the Sightron Siii) but that weight savings is because the X50 does not have illuminated reticle, which I'm fine with. I also like the X50's reticle better than any of the Siii reticle choices.
Just another option to consider.
(Mine ranges better than any other scope I've tried or looked through. Ranging by focus is a very field target specific thing to ask of a scope but my X50 does it extremely well.)