Apart from Flarum, I am only using WoltLabs for one of my projects.
I have used pretty much every forum software there is out there and each have their pros and cons.
Why do you think you cannot use Flarum in a semi-production environment now? Provided you try and keep your instance as stock as possible, basically running no or very little extensions, you shouldn't run into too many issues when upgrading to new versions and eventually the stable version.
Give FluxBB a go if you want something light and fast. It is developed by our very own Franz. ?
