Is the GH3 shutter silent only with slow speeds?

If I understand the review by Adam Wilt (on the rumors site), the GH3 (and I guess G5) shutter can only shoot at very slow shutter speeds in its silent mode.  He gives a 1/12th figure at 3:2, a bit faster at 16:9 and a bit slower at 4:3.  If this is so, it certainly limits the value of the feature.  Generally, we would want a silent shutter when taking photos of people - who tend to move.  Am I missing something or just plain misunderstanding?  To me, a silent shutter would be a reason to get a GH3 rather than an EM5 to go along with my current EM5 and GH2.

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W Alex Stewart