If you're ensuring safe weapons-handling, go for it. I see the point - I get what you're trying to do.
Having thought about it as a training technique, this is what I have to offer.
Fundamentals - What is it you're doing / what do you want to accomplish?
Balance.
When I played hockey we grappled on skates. Taught you when to push, pull, give, and take. While this is similar to what you'd be after, I see the coefficient of drag (the wheels) not giving you a fair re-creation of what will happen when you're on your feet (shoes to ground).
But yes, I think it will develop your balance.
(perhaps, not the best way)
Remember that, in balance, it is not solely a function of your equilibrium but the necessary muscles to effect your counter-balance. i.e. your stabilizer muscles. Those need to be trained and worked just as importantly as your overall 'sense' of balance.
Therefore, without drawing or gun handling, the best way I see to increase your balance AND strengthen your stabilizers is to use, (what I will call) an "ankle balancer". And I'll explain.
When I tore my ACL, MCL, PCL part of my physical rehabilitation was to use a round flat device that had a small ball in the bottom center. It was wobbly to stand on, forcing one or two ankles to move in all directions, flexing and relaxing to maintain your balance. There is a kids toy that is almost identical, its a bouncy thing. After about 5 minutes an ankle, those muscles and tendons were screaming from an intense workout.
If this balance your after is based on maintaining your center of balance or rather not being knocked off balance during the initial response to a threat, I'd highly recommend training with a partner. I've always found role-playing (for some reason) silly in nature, but invaluable as a practice. Most street encounters will stem from one person touching another. An elbow, a finger in the chest or face, a shove.
Going hands on is a great way to work on your balance. A wife, training partner, or friend. You're not trying to Mike Tyson Knockout anyone, you want a stun that makes them back up, give you that crucial time and distance to draw. When it comes to shoves or pushing, I personally, try to train not to push back. Taking a few extra steps back to regain balance, I can lower my and widen my gate for an attack and I've just gotten out of the kill box by backing away. Now I've got time and space to draw and present.
With a little modification, I think you have a great idea based on some sound fundamental principles. Good job on that one! Keep em' coming.
