I thought about enabling all my accounts on this but decided against it. Couple reasons:

1. If you read the FAQ, they mention "future benefits". What if every blizzard.net account gets 1 shot at a SC2/Diablo2/etc beta key, no matter how many sub-wow accounts you have? I'd rather have 5 (or whatever) seperate blizzard.net accounts that each have a shot at a beta key than 1 account that has 1 shot. I'm sure more stuff will pop up too, and its easier merging later down the road than now when the benefits are unclear.

2. As discussed, once you have multiple wow accounts on one blizzard account you have an extra step upon login. Does it remember what wow account you used last, so you can just hit return? If not, its adding an extra step to login, especially if you have to tab through and select on every window (UGH!)

3. Its irreversible. If I could split the account back out then I'd be fine, but its a one way step and the benefits are fairly minor (the number of times I login to web admin pages is maybe once every 4 months).

re: authenticators, I'd guess its basically a algo that streams a series of numbers till the battery dies, and the seed is the serial number. ie if anyone is able to grab your auths serial number they could theoretically 100% clone your authenticator (I'm basing this on the assumption that the only thing the server knows is the serial number, so probably the algorithm essentially takes as input the serial number and current time and returns a generated number -- an iphone app would simply ask for your serial number and be able to keep up exactly always, hell you could probably write a desktop app to do this too... kind of scary actually).