Review update with the Shooting Sight trigger: The purchasing process went smoothly and the product itself is very nicely made (it's clear a lot of research went into the manufacturing if you read more about it). Installation took me a little time as I had to make sure I got all of the springs together correctly (pictures help!). The hammer seemed to bind just slightly when drying firing and releasing by hand - I called SS (who answered promptly and clearly has researched the operation of the trigger and system extensively). There didn't seem to be any issues and it might been a trait of the factory setup that I just never noticed.

The SS trigger includes a heavier spring for US made Sigs that apparently only include one - I opted to keep the dual disconnecter springs from the factory.

Shooting with the trigger is improved. The "three stage" feeling of the trigger is smoother now with a clear first stage then clean break on the second as intended. I recommend the trigger to anyone looking for an improved factory feel without compromise.