I'm not using Giga or VSL live, but I would consider getting an AKAI sampler and converting some giga patches to akai format for that. You just can't afford to have hanging notes or dropouts when playing live. It would make you look like a sloppy player.
I use VSL live, all the time. I love it. The pitched percussion are great in different combinations, and the Horizon soprano sax is more fun than a barrel of monkeys with a wind controller.
There is no dropout or hung note problem with Giga if you use it live with a nice rig. It's got better performance than any keyboard I've ever owned. Absolutely no problems at all. Well, actually one. I had an outdoor appearance once where the sun was so bright that I couldn't read the monitor. I had to improvise a little hood. Other than that, perfect.