So I saw this interview by inragnetv with Jim Sullivan...

https://www.youtube.com/watch?v=gOUKXIrDE0I

Also saw that surefire has something that incorporates some but maybe ?? not all of those improvements...

https://www.youtube.com/watch?v=L8JWUvt65eo

I'm also aware of various carrier weight systems and the FERFRANS rate reducer.

Of everything I have ever seen this Sullivan and Surefire system seems by far the most interesting and promising. Especially as it is the only one that increases the length of bolt travel. Additionally the bidirectionally sprung weight and different cam path allowing for longer lock time is of great interest.

Is anyone aware of anything else that would be competitive with those features and not just a weight or other rate reducer?

Other things I might like to see may include elimination of the forward assist notches (never happen on a military gun but I can dream), and a reduction in the width of the hammer slot if reasonably feasible.