It is easy enough to find out what has changed between two different versions of a beta. It took me a couple of minutes, using araxis merge, to compare two D7B7 and D7B8 folders and find about 219 differences (if my memory serves me correctly, I have a copy of the report some where). It is also really not difficult to manually upgrade your site between versions (as long as you are careful), it will just take a bit of time. Replace the files that need replacing, make a note of the differences in the see more SQL files and either add, update, modify, delete what ever is appropriate, in the database, using whatever client tool you use to access your MySQL. Most will use phpMyAdmin which comes with their cpanel.
That all said, I cannot be bothered to spend my time manually upgrading between versions, I will just keep my sites on the current beta verison and upgrade directly to some stable RC. I have spent enough time p*ssing into the wind.