Plenty of people are running the beta firmwares, mostly because of the compatibility issues with new BDs. I still follow the 83 thread on AVS (even though I don't plan to buy the player now). I've never seen any problem reported with someone upgrading to a beta release. The only case I saw trouble was someone trying to downgrade to a much older release which bricked his player, and it has to be sent to Oppo for repair (the issue was Oppo changed something in the newer revisions of the player, all firmware releases since that change were compatible, but the old one he tried didn't know how to deal with the difference).
But yeah, that's correct. The subtitle moving feature isn't completely bug-free yet, but seems to work in most cases. So it isn't in the official release, but will end up there once they feel it is working properly. There's also a problem with the current beta, and people who have modded their players for HD-SDI output. Oppo is aware of the problem and trying to fix it. Now, that's actually really impressive, they're trying to see if they can make a third-party modification (that basically illegal, because it bypasses the HDCP) continue to work with new firmwares.