The Ksyrium SLs I have are rigid as hell and lethally efficient, they make a big difference to climbing, which just seems so effortless. However they are pretty high-tech in the way they are constructed and although they come with a really easy-looking spoke key, I would be terrified to mess with the spokes.
On the other hand if you bought hand-built you get the satisfaction of supporting a craftsman and the lifelong guarantee and after-sales service that brings. Plus you get the enjoyment of discussing the build and absorbing some of the aura of experience from the maker.