I'd question the choice of machineable stainless to make a striker for a defensive pistol. I'd prefer a suitable carbon alloy tool steel machined striker.
If faced with the choice of machined stainless or an MIM striker, i'd likely opt for the MIM unit. MIM parts strike no fear in my heart. I work in heavy industry and some of the MIM components used endure incredible wear cycles. I understand that there has been some breakage in factory strikers, and even a 1% rate raises my eyebrows.
Machined stainless is generally a trade-off. Also useful in many applications, but there are many variables as to hardening and heat treating. I don't see the need for heat or corrosion resistance in a defensive pistol striker, so i'd choose different properties and a different steel.
All of this said, and i don't know what steel they are using for the sig striker. More questions than answers, but i'm pretty sure that sig will nail it down...
