The ultimate point, I think, is the caching of the templates in memory. As for storage ... access from multiple servers certainly is an issue. I can think of reasons for or against it, but until I've benchmarked a few solutions in a serious environment (few million hits a day) I don't want to out-guess them.

Either way, you don't have to sell me on the inconveniences of the system. Nearly every design decision in Slash is sacrificing something, often ease of use or development, in the name of speed or security. Not the way I would do it at all. A couple extra web server machines are a lot cheaper than developer time in the long run.