speccyverse: PMT isn't essential for serving. Lots of the high-performance web servers don't use the fork() model, and only have one process multiplex it all. (Which is how Netplex and that other free server do it, IIRC.)
What is essential is a fast file system, a decent IP stack, and reliability. RISC OS is too trivial to crash remotely if there's the tiniest of bugs in your server software.