If you wanted a decocker, you should've gotten the Match rather than the Super Match. The Super Match is SAO, and they don't have a decocker option.
I've had both models and they're fine-shooting .45s. My Super Match, when it locked back after the last shot, required the use of both hands to release the slide: one on the lever and the other working the slide. Mine was an early one, and many of them were apparently over-sprung (recoil springs) from the factory. Had I kept it, I probably would have cut a coil off the recoil spring, as SIG claimed there wasn't a lighter one available from them.
Yes, I agree, it's a tough slide to move. Would have been fine 30-40 years ago.
It does help once the optics are mounted, I know I should not use them to move the slide, just gives me a better grip.
They both are 5". The Fjestad Blue Book shows them both under the MATCH listing, noting that the Super Match is SAO and comes with gorgeous custom shop wood grips! But you should know about the grips.
The only thing that might be significantly different is the P220 X-Five, very rare here in the U.S. -- I've only seen photos on the 'net -- and I'd hate to find out what one of them costs...
The Blue Book says that the Elite Match became standard during 2010.
I usually shoot Penn Bullets and that is what I used there. If you want to shoot jacketed, the 185 HP from Nosler is the one to go with. The Penn 200 SWC is maybe even a touch better than the 185. I never had any good luck with Berrys when it comes to accuracy. I tried them in both 9mm and 45, they shot okay at best for me.
I do ammo accuracy testing from a rest. The objective is to eliminate as many variables as you can to see what the ammo is doing. The gun, the ammo and the shooter all have error. If you don't reduce some of the error, you will not get the best end result.