[meaubry]

We built a prototype of this style of launcher and others too. Seemed to me to very reliable and accurate, I suppose it all depends on how you build it. As far as surgical tubing goes, if handled properly it will work just fine. We have used this material many times for counter balancing articulating arms with zero failures in 11 years.
I believe if you created a simple prototype you would see how well it works - the difficulty is in the reload time and catch/release mechanism.