What to do?

I recently bought one of those wireless earbuds from Amazon. I spent some time researching all the available options and finally picked this particular one. It was highly rated on Amazon 5 stars from 54 reviewers (most of them "verified purchase"). Not great but not bad. Anyway, the earbuds arrived and I found this in the box:

Hmm, OK. Very mysterious. As instructed, I sent them an email for further information. Here's what I received:

Funny thing is I really like the ear buds. Excellent build quality and thus far, great performance. They reconnect to my phone 2-3 seconds after taking them out of the case. It's easy to create a good seal...sometimes so good I get that underwater feeling one gets with noise cancelling headphones. Even without the 40% incentive, I would have written a review...that's how much I like the ear buds. But now I feel weird about doing it. I wonder how many of those 54 5-star reviews were motivated by a 40% discount.

As for the 40% discount, I doubt if I'll ever use it. Not unless this set stop working and I decide to buy another from the same company.

So what should I do?

• Don't write a review, don't take the 40% coupon
• Don't write a review, take the 40% coupon
• Write a review but don't take the 40% coupon
• Write a review, take the 40% and encourage this shady practice