I use the lever to push in and close the stem if i am setting the time but then I re-open the lever to wind the watch. Not sure if this is right or wrong but I have never had a problem with this process.
I have both. The 312 has turned into a business or wear to work watch. I have have it on a gen gator and the date comes in very handy at work. It feels dressier than the 111M which has turned into more of a weekend or evening watch along with my 177M. I don't need to know the date on weekends or evenings. I love all three.
I could imagine someone getting a Pam as a gift. Someone who could give a [censored] about watches or the brand. They might find the CG a pain in the ass (it actually kind of is when you think about winding and setting the time with it in place). 99% of watches have no guard like this so I could see them removing it purely from an "easier to use" reason. Kind of like a "lazy man Pam mod".