An Op had a pair and I got to see it in action. They're very cool and handy for moving machines around, and much smaller than a pin dolly so you can throw them in your trunk or whatever. Not sure about leaving them on full time.

Your legs + casters would work, but could be a big PITA if the game is up against a wall and/or surrounded by other games, making it difficult to get to the leg bolts in the back. The skates are nice because you can crawl under a game.