Will a stainless last longer? Probably. Do I really worry about that? No. I've had a number of SIGs, all alloy frames. Some new, some from the 90s, and some from the 80s. They've all been fine. As has been said by the time you "wear it out" from shooting you'll have spent more than ten times its value in ammo. I do recommend a good grease on the rails.
Know the status of your weapon
Keep your muzzle oriented so that no one will be hurt if the firearm discharges
Keep your finger off the trigger until you have an adequate sight picture
Maintain situational awareness