I know this is ragdoll physics, and not everything is supposed to be realistic.
However, I think it would be a neat mod/game rule in which grip will be lost after a certian amount of pressure is met. This would be neat for breaking out of holds or pin downs.

Not a bad idea (for sparring w/ weapons)

However, for aikido, i don't support this.

Well, I don't like the idea to be honest.
1. It would ruin Akido (But other's kind of agree with me on that).
2. In spars if you want to ungrab it would be much better to just ungrab, then to randomly have your grab stop working. (But who grabs in a spar?).
3. In weapon mods, it would just make you drop your weapon unnessecarily. It would be a clumsy option at best.

Not supported.

Not Supported for 2 reasons.
1. It's pointless, the generally kinda main idea is to have fun. Do you think it'd be fun having to control tiny finger joints to grab stuff, and then randomly have your hand let go because of a glitch in the Matrix?
2. I forget what I was gonna put here.

It could be a gamerule, just like dismemberment, i.e. it can be turned off or you can set a threshold for it. There's no reason why it would on by a default for all the existing mods, especially considering the fact that it changes the gameplay and probably wouldn't be compatible with older clients.

Sometimes when you grab someone and pull too hard, your wrist breaks off. A new thing you could try is to set the ungrab threshold the same as the dismemberment threshold, so you're more likely to just let go instead of your wrist breaking off.

One of the changes to the serverlist is to grey out the rooms which you can't join. So if there's a room using a gamerule which your client doesn't support, you'd hope to see a message saying something like "you need version 4.x to join this room"

There are a lot of users who don't update toribash. There is no intention to make changes which will break the older versions of toribash. Especially if it changes gameplay.

I like this idea, seems to add another dimension into the fight, you know not to yank to hard or you might lose your grip.
~Supportation

I like this, why? So that noobs in Judo will actually let go for once.

Isn't a bad idea, but it will destroy the aikido. Anyways, this realistic idea don't will work in toribash. The fracture and dismemberment is Ok.
Not supported too.

For all of you saying this would destroy Aikido, this could just as easily be toggled off for certain mods. And in weapon mods, it would be pressure based, so unless you plunge your sword into the ground to try to look badass, you shouldn't have many problems.

Anyways, would add a new element of actually having to think about where you're grabbing. I like it as a toggle-able option.
~supported

I think there should be a feature added where there is a way to inflict "pain" on the opposing tori. It would definitely be toggle able. Let's say that your opponent is grabbing your hand. You pull him forward but you can't generate enough power to frac his elbow. You could press his elbow inwards and that could create some "pain". If enough pain is generated, then the grab will break. This could also be used as an instawin goal for some mods. You could pin your opponent or put them in a painful position. If the threshold is reached, then it is an instawin.