You say "giving away", I see "being forced to buy, then later apply for some form of or equivalent of rebate, which I've had really shitty past experiences with by virtually every single company ever offering a rebate in any way"

That's the biggest stopper for me.

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On top of that, think of it this way: if someone writes a negative review, wouldn't they innately feel that you wouldn't reimburse them? So you are basically "paying for positive reviews" psychologically, rather than the more fair reviews if they were compensated in the first place IMHO