issue #1 sounds like he was limp wristing it if it only happened with him and no one else.
issue #2 could be a mag issue. I know I read a while back that people were having issues the 15rnd mag not working right with the "c" versions. Have to do a search.
Personally I have not...
I made my own based strongly in the crossbreed supertuck. It rides very nice, very easily concealed with jeans or shorts and a shirt. Barely tell it's there some days.
In the same boat as you. Really would like the fiber sights for my sr40. The light blacks out the sights at night, the laser gives a good alignment but no where near the fixed sights as far as trusting the accuracy
I don't think you will have any issues with holding on to it. The 40c has a relatively light recoil and does not have much pop. The springs easily absorb a lot of the felt recoil.
My sr40's trigger seemed to lighten up after 200 rounds or so. The sr40c felt great right out of the box. Trigger was a little gritty but cleaned and lubed fixed that right up.
I like the IWB carry, for me I like out right around the 7:30/8 position (lefty). Basically a little before my back pocket. Anything beyond that doesn't feel comfortable.
So the shield us a little thinner and lighter but lacks in the ammo capacity. The trigger seems real light on the sr40c not sure on poundage but its pretty light, and the recoil is very manageable IMO.