Forum OpenACS Q&A: Response to Building a high-capacity, high-availability OpenACS solution...

As far as hardware, I can't help. But in regards to the templating
system, I don't believe Karl's system is done yet, nor ported to
the ACS. ArsDigita is beginning to move over to a more
template-based system, but they're not there yet so most of the
work still has to be done with Tcl scripts. While they're messy to
edit, Tcl scripts will still give you the maximum flexibility. For any
serious site, they're the only way to go (right now). Unfortunately,
the downside is that they're hard to upgrade when new versions
of the ACS come out. Hopefully however, ArsDigita will have
abstracted out most of the stuff into templates by 4.0 so it won't
be as big an issue.