Guillermo,
Thank you for your reply!
When I mentioned performance issues - I don't have any hard facts, and I didn't want to start yet another *nix vs windows war... but I just get the "feeling" that Apache runs better on linux and IIS runs better on windows. Whether this is a justified opinion or not is another matter. One might argue that PHP runs better on Apache and that is more important? I don't know.
When you mention possible future limitations: Are any possible future limitations of PHP on IIS anticipated? I expect this comment more of a "what if?" scenario. That's certainly something to consider!
So far the documentation collated on this site seems excellent. And I expect I'll do about a thousand "dry runs" of the migration process on test servers.
Cheers,