The standard GI handle has done ok for 45 years. I'm not seeing any reasons for it to be changed since it does all it needs to do in real combat against all the enemies we have faced in various environments.
The fancy handles address issues only found in competition where specific things are done to the weapon that force its adoption, like, light loads to reduce recoil, or stages were reloads are a forced requirement. For the most part those are artificially induced. Competition deliberately sets up these events to sort out the goats from the sheep among the top contestants. It's not real life.
The M16 series has a bolt hold open, on the last round fired it's held back - you drop the empty, insert new, hit the release and you are in action again. With the ergonomics already sorted out, you don't even remove your eye from the rear sight. Doing so only increases risk.
What do you need a specially enhanced handle for when the real skill is quickly recharging the mag well? You don't have to pull the bolt back when it automatically stays back. Otherwise, you only use it to charge the first round. The other 299 will follow suit if you do your part.
Stoner was a Marine and he knew what he was doing.