Not sure who makes the SIG red dot sight.
I am sure that I wouldn't jump on one till they've been out there long enough for people to use them and find out how well they hold up under use/abuse.
Why pay to be a guinea pig for a big company's products?
I don't have experience with SIG's red dots but I've got a SIG rifle they modified once, then quit making because they had a better idea, then quit supporting with parts and then dropped the improved model that replaced it without every finished the development/support for, etc., etc., etc.
In other words, the SIG pistols may be great, but I'd look at a well established sight made by a company that has a record of support for their products and customers (trijicon, burris, vortex, leupold, any more???).