Ok, you asked for opinions/experiences, so......mine's a little different. I personally have a very strong dislike for all those "balancing system" thingys -- basically, look at how the ropes work. Everytime a horse's bum muscles move, he gets punished with uneven pressure on the bit. All this teaches him is how to stop getting tugged in the mouth by setting his head in such a way that the rope doesn't get him. He's not learning how to use impulsion in his back end at all. IMHO, I'd throw all of them in the trash as the gimmicks they are -- I'm sure if you strap a horse into it, you'll see him going around in an outline pretty quick -- because he doesn't want to keep getting pulled on. I have to give them credit for convincing people that they should pay $150 for a piece of rope that says Pessoa on it though....
I'm not anti-tool, and I love using a loose set of side reins to help my horse build his topline while on the longe. Spend your money on a nice bridle or something instead.

Solaris -- 16 hh Appendix Quarter Horse = MY DREAM COME TRUE!