Personally, I think the Extendo grip looks cool, but I find it too obstructive when fighting for example, so I think it'd be cool if there was an option in the client config file to disable it's rendering when you have an item equipped.

Like most model based things you I assume you could just make a resource pack for this, although a config option would be easier.

I haven't thought about that actually. But seeing that the extendogrip also renders the thing you're using, I don't think you could fully remove it