Chris makes a great point about what makes for excellent training(for some) might not be wise to have in a contest. I really like the Tips Tester and I know it makes me stronger in other areas of grip(like the Tips Tester, LOL). However, I always put a disclaimer on my vids to be careful when using the TT and that I would advise NOT maxing on it. I had the TT at contest 2 years ago and many were complaining of funkiness in fingers- that is not good and I wont have that at my contest again. I
I believe every contest should have a sledgehammer or pickaxe event. Although they can hurt you if not conditioned, at least you can train(be creative)without having to buy specific implement.
One last point, everybody would agree that anything "could" injury somebody- Heck, I hurt my middle finger tendon on the freakin IM hub last Decmeber and still not the same. But, like what was mentioned above, any max lift finger tip pressure, etc really brings up level of unsafe contest and not really fun experience.
A filed gripper is still the same as it was before filing. Only the very last range is different. And so if the gripper was easy to you before, you'd be able to power through the filed range.
I think the effectiveness of filing is vastly overrated. Tbh I'm unsure if it has any benefit at all 🤔