With out a doubt, it would be the SI Device. With all of the other drills and equipment out there, there is one flaw in them. For every drill you work, something in what you are doing is not the same as vaulting. So when you practice one drill to work on a Phase of your vault, the muscle memory you are working includes 2-3 muscle memory motions that are not involved in the vault. ie a high bar, your hands are not even with each other and the shoulders are in a different position on a high bar than when vaulting.
The SI device lets you practice the vault without the run up, in all types of weather(if you place it indoors) but with all of the muscle memory and feel of a real vault. Check out the web site, the demo video speaks for itself. It may cost some money but think of all the time spent on rock backs and other drills. At a $1.00 per drill it will add up in no time.
With beginning vaulters there is a fear when running down the runway and vaulting. The SI device will let them gain confidence and desire for the vault and they can overcome the bad planting techniques faster than most beginners have when they start without it. Just my personal opinion.
My personal opinion is that it is worth the money if you are serious about teaching the vault. Next to a pit and poles and coaching, it is the best tool out there. The idea is so simple, I do not know why it took 40 years to be developed.
Check out the web site, get a free video, check and see who in your area has one, and try it. After you do, you may pawn some poles to get it. Or at least beg you wife for an early Christmas present as I did.
I saw it a year and a half ago, and wanted one. I showed it to some other coaches. They bought one and I was able to take some athletes to try it. It is so awesome that I got one myself and use it at my club. The high school I coach at had kids finishing at the meets and going into the practice room with my vaulters to try it out. It is just the best. I can do more quality practices and less quantity because, the gym ceiling rope, high bar, and rock back drills can be combined on this machine. We can now focus more time on drills for core strength and conditioning than on trying to work 6-8 drills for the vault. The feel and timing is the same as a vault that is done correct. The best part, is they can see the amount of core strength it takes and I seem to get less of a hassle when we work core and are not on the runway. They get it faster and want to get better and can actually feel like they are turning the corner. Best of all they feel a sense of accomplishment.
The run up and plant is 90% of a vault for an experienced vaulter. If they are slower than normal or their step is off, it will be a bad day. The main fear that a beginning vaulter has is the takeoff. It is hard to teach vaulting when you say it was hard to work the top of your vault because you were out or under on the vault, your plant was to low, you slowed down in the last 3 steps. They have so much going through their heads, that they will have a hard time grasping what you are telling them, when all they are thinking is, "I hope I hit the center of the pit."
With the SI Device I can start teaching beginners the vault without the runway. From day 1 they are getting air time without a pit. I would not suggest this, but if I was in the situation without a pit. I think you could teach a kid to vault with a pole, a sliding box and the SI Device. I think it could be done. That is not a substitution for the real thing but a personal viewpoint.
http://www.swingupinvert.com/swing_up_history.htm
Thanks guys, I love my SI Device.
Coach Scott