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If you are asking them to write about you and give their honest impression of your product/service you are marketing. If you are asking them to write about you AND asking for a followable links you are violating Google's Webmaster Guidelines. What you are doing is clearly walking the line between these, but my opinion without having actually seen any of the posts/links is that you are leaning toward the marketing side. Where you might run into trouble is if this tactic represents a huge proportion (say about half or more) of your total links. Relying to heavily on any one link building strategy, especially "iffy" ones like this, is never a good idea. Round out your link profile. If you need to pause this campaign while you do so then so-be-it.

Google can preach all they like about lessening the weight of EMDs but fact is they still have massive prominence. As long as it's not too long, I'd go for the EMD.