45 super is getting to 10mm levels of poke but that is still not crazy or anything. Surely without a different recoil spring it is going to hammer the hell out of the gun. Even with a much heavier spring it's hard to say as most platforms for 45 can be made to run 10mm but they have more metal since the 10mm is a smaller diameter round. And who knows if the polymer components would handle it well?
No matter what brand or caliber the factory recoil spring is always on the light side to ensure reliable cycling with light target loads so using more stout loads like defense and +P is already causing more abuse.
Your gun was designed to shoot 45ACP so shoot that. Some occasional +p isn't likely to hurt but if you want more poke than 9/40/45 then you need to get a gun designed for it. Perhaps Walther will come out with a 10mm in the future to solve your woes. If they make a paddle one, ideally in P99AS format I'll be lined up.
