One of the finest Aikido men I have ever met was Mits Yamashita of Yoshinkan fame. His courage in calling helio Gracie's grappling, "Aikido on the ground". is obviously famous.
In law enforcement, I know allot of focus has been on training police to understand groundwork.
1) Are police getting into it?
2) Is there any work being done to include the hidden knife once the fight goes to the ground?
3) How is ground grappling and gun retention being delt with?
There is a venture now into groundwork, however, in my opinion, it's still very much in its beginning phases. Therefore, things like utilizing one's other weapons (e.g. knives) is not yet all it can be. Additionally, things like having knives or not is not yet universal - not everyone wears them, so it's hard to make a system around them. Moreover, those that wear knives wear them in their own personal places - often with little thought of how said place affects deployment. As for gun retention, I think things are even worse. The stuff I've seen is too akin to sport ground-fighting techniques - which doesn't really work all that well when one is wearing a waist full of weapons. For example, one technique asks to do a kimura against a gun take-away attempt. The technique probably works well in unarmed fighting, but on the job...? There's a lot of shortcomings to it. Personally, I'm working on developing some other ground-fighting options, options that are all geared toward getting back up and having full access to one's arsenal again. The efforts seem promising. I will try to post you two videos of this - try to film it this weekend and get up on the net as well, so you can see what I'm trying to talk about.
From the videos, we can talk more. You are asking some very good questions - thanks for raising them in the thread.