Yet another SDM owner here
Being in Victoria where SDM scopes are made I'd say theres no question about which one to buy.
Apart from the advantages of local support (which I did need in one instance), Peter is happy to customise and build to your spec as was the case for me. I got exactly what I specified whereas with obsession you only have a range of cookie-cutter products to choose from.
Peter is always looking for ways to improve the scopes and mine has a few convenience features not found in other scopes, such as a zipper in the bottom of the shroud to facilitate easy access to the mirror box lid, and two piece transport handles which means no messing around in the field bolting/unbolting handles to mirror boxes just to move the scope.