I think your main problem is going to be with threading. We have run Zope on Solaris for quite some time, and there was always nagging doubts with python and threading. We are now running all new Zope installations on linux (SUSE) and are having no problems.
A google on zope/python/solaris will turn up all sorts of information - not all of it is going to be fun reading... :( cheers, Tone
