Using Yosemite for web development
From my personal experience, Yosemite isn't really too bad in terms of bugginess. It's quite unlikely that you will suffer data loss, but take backups as always. I have had no more problems running on Yosemite than Mavericks (aside from some cosmetic issues related to Dark Mode and reducing transparency).

That said, it really depends on what you use for web development. TextMate, iTerm, and Xcode work really well, but if you've got another IDE running you might want to  wait until you know it works well with Yosemite. I'm also a big fan of Alfred and Karabiner, both of which have official support for it.

Also, what reason do you have to run Yosemite? Even if it is low risk, it isn't worth the trouble to just be able to use the flashy new GUI.

The legal limitations are pretty severe, however:


  […] don’t blog, post screen shots, tweet or publicly post information about the pre-release Apple software, and don't discuss the pre-release Apple software with or demonstrate it to others who are not in the OS X Beta Program.


In a work environment it's going to be difficult to avoid discussing or demonstrating it to people not in the program.

So in this instance, it's probably a good idea to wait until 10.10 is publicly released, as Apple also warns against using it on production machines or business-critical ones.