I personally run the software in production however it is purely the core features I am using. Basically what you get on installation is what I'm using; I don't have any extensions or additional features installed until stable is here for peace of mind and to avoid the headache of fixing bugs and any other errors that may arise during the update/upgrade processes.
If you have some know how in coding then by all means take the risk but the warning is there as a "just in case". Of course the core development team do their absolute best to prevent any of these errors to occur but that isn't to say that it cannot happen.
Better to be safe than sorry. ? But by no means is it still in beta because it is a test run or temporary forum software.