I shoot an Encore withe the TC factory rubber grips. What can happen with heavy recoil (at least with my Encore) is that the pin will move from side to side. I didn't notice the problem until I shot a few times, then the gun opened sorta funny one time. It was then I noticed that the factory rubber grips will allow the pin to move from side to side a little. Not really a problem, but I could see the locking pin being OK if you worry about that sort of thing.
I don't worry about it, just poke the pin back in place. It doesn't happen very often, so I don't really see the "locking" pin being worth the $50.00, not to me anyway. I cerainly can't see it improving accuracy to any measurable degree.