Too short, at least if it is an actual beta with the intention to find errors and fix them afterwards, and not basically a time limited demo as many public betas recently have been.
Also as they told us on BlizzConline it is basically the same game with a new graphics/audio engine running on top of it, so the chance for game breaking bugs should be not that high, unless Multiplayer which integrates new Battle.net and therefore should need a lot more of code rewriting, prone to introducing new errors.
The release date might still be realistic, but I do not see a reason for for the long break between technical alpha and “multiplayer beta”.
As the game seems to be pretty stable as it is I see no reason why not to start the multiplayer alpha/beta whatever it will be called much earlier, maybe at the beginning of May. There is no real reason to hold it back and waste time, you also do not have to fix everything from one alpha/beta phase to the next, they are mainly to detect bugs. Known bugs have to be fixed for the release but not necessarily for the next testing stage.
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