I say, go with the machine posts. I test-mounted one of my joysticks with them the other day, and I was absolutely thrilled with the results. Even though I'm flush mounting the joysticks (so there won't be any visible hardware), I am very pleased with how flat they mount. Even if you are going to have visible bolts, these would be better than carriage bolts since they are so flat, thus making them better for playing games. At about a buck a piece, they're a little pricey, but worth it.