Erm... far from being a guru, I've tried php on Sun - mostly Ultras and Sparc, and it works FINE! 😃
We're currently running Linux(!) on a Ultra 60, but are going back to SunOs in about a month or so. This is our home server, and the combination of Ultrasparc and Linux is shockingly fast! 🆒
On our production server, we're exchanging a puny little pc for a Blade soon - looking forward to that.
In my opinion there's as easy to put up a site on Sun as it is on Linux - provided you use Apache/mysql/php as sw.
Haven't tested with other sw, so it's a bit difficult to say for pros and cons.
knutm