My bad. The [BreezeController] attribute was too aggressive in removing ambient action filters; it apparently removed the filter responsible for the [Authorize] attribute. I have a fix that is currently under review.
The "[ODataActionFilter, JsonFormatter]" formula didn't suffer from this problem because it didn't remove any existing filters. Of course that was a problem too. If you used the new ASP.NET MVC SPA template ... and I think you are! ... then its QueryFilterProvider conflicted with our ODataActionFilter ... which is why we invented the [BreezeController] attribute and why, I think, that you're getting the error about not supporting querying. Can you confirm that you built your app from that SPA template?
Btw ... what 'Posts' action are you talking about? The "Breeze.MVC4WebApiClientSample" does not have such an action.
In any case, we expect to have the [BreezeController] attribute working properly with [Authorize] very soon.