I am.
Yes, its expensive but so is vB compared to phpBB
As far as Zend, I'm not bothered - a company has too much at stake to try and be devious with encrypted source files. And lets face it, 99% of all programs are encrypted anyway - its just rare to find php files that way.
My only grievence lies in the copyright enforcement. I would easily pay good money for a brand free option. However if it bothered me enough - I wouldnt have bought it. Thats the power of being a consumer!