[development] Stable entity type ids in D7?

I have a couple dozen fields in my db. When we went from alpha6 to alpha7, the entity type id for comment changed from 2 to 1, and node from 1 to 2. I had to change all the ETID columns for my field instances, as well as the node blobs where entity type id is also kept. Now in beta1, comment is back to being 2, and node is back to being 1, and all my node fields have 2 in the entity type id and node blob and my fields aren't listed again on the content type. Is there a reason this keeps changing? Is there a way I can get back into synch more easily than doing all that work again? I could just change the entity types, but I don't want to have to do that again with every release. Jeff