Great to see you guys are working on the unit as well. (New rev. shipping from 16-04-2015.)
I got mine on 05-03-2015, it's a bit sad I missed that hardware update.

Should I worry?

I ordered mine on the 11th of april. I guess the improvement is not that important but I feel some disagreement since it is a bit unfair to inform customer few days after the release. Should I know such a imminent improvement, for sure I would have awaited for some 4 days more.

Anyway, my module works perfect and I'm more than happy with it but things could have been handled in a more customer respecting manner .

Don't worry, there is really no reason to switch to the latest revision. For 99.99% customers there is no difference.
Main difference is for us, because manufacturing process is easier with achieving even better quality.

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Spirit System developer