Do you let people beta test?
Absolutely!
Within Spaz, you can enable "check for test versions" in Preferences > Upgrades. That will tell you when more stable testing builds are available.
If you really want to be cutting edge, keep an eye on @spaz on Twitter, where we will sometime announce builds that aren't stable enough go into the testing feed.
If you're especially ambitious, you can
build from source at any time.