I have the P226 Legion SAO and am seriously impressed. I just had it out for the first time yesterday, and it took my personal accuracy to an entirely new level. The thing shoots like a frigging laser, no joke. I have a Trijicon RMR LED sight on mine and the combination is simply wicked. In my view the P226 Legion SAO is money very well spent. I do not believe that there is any finer 9mm handgun on the planet. I have a Beretta M9A3, Sphinx SDP Compact, CZ Shadow , STI .45 Tactical SS M1911A1, and several other top-end 9mm and .45 cal handguns by which to judge, and there is simply no comparison. The Sig Legion P226 SAO is the hands-down winner of the bunch, no question. Try one, and you will discover what I now know. The P226 SAO is the softest shooting, most accurate handgun with the best single-action trigger that I have ever experienced, bar none. It gives custom tuned "race guns" a run for their money, it is really that good.
For the OP, you can ride your strong-side thumb on the Safety without interfering with the Slide Stop. The Slide Stop is very low profile such that you don't notice it unless you are looking for it. That said, if you ride the Safety with your thumb you may have difficulty manipulating the Slide Stop when you want to. I have the distinct impression that this will require some practice to overcome.
Another thing that I have noticed is that you cannot release the Safety if you already have pressure on the trigger. The safety will bind up with the trigger pull, rendering the gun non-functional. You then have to release the trigger and wait for the Thumb-Safety mechanism to "click" before pushing the Safety down into the firing position. Definitely not a show-stopper, just something to be aware of during dry-fire and live practice. You can't ride the trigger when manipulating the safety, which is probably a bad habit to begin with.
For the fellow that just missed out on buying one, be patient and place an order through your LGS to M.D. Charlton. That's what I did. It took a couple of anxious months but eventually the happy day arrived. The wait was totally worth it. Whatever you do, don't give up on the Sig SAO Legion just because they are sold out everywhere you look. There is a very good reason for that. Order one and you won't regret it....