And yet another vote for Shubb. I've had the same couple of ones for years. They can be placed or removed in 2 seconds. It is also very easy to adjust the tension in 2 seconds. Imagine a program going back and forth between capo or no capo and having to have the capo at various frets. Imagine all of that happening in a set. You would want to quickly, subtly make the preparations between each piece. The Shubb is fully capable of doing the job and for a very friendly price.
Dr. Todd Tipton, Noda Guitar Studio
Charlotte, NC, USA (available via Skype)