Speaking in general so that it maybe clear for others...
I know development has been working hard to make upgrading from each build possible and that is still the plan. But there is no true guarantee until the final version. From that point on, yes, there will be a guaranteed upgrade path. But during beta, while it is the goal, there is no 100% guarantee.
I know some people have been using the beta in production (myself included). But unless you are willing to take the risk, you should either stick to testing or wait until the final release. Testing of course is encouraged as it will help weed out bugs or issues in the final release.