Has anyone ever sold the rights to an image as DT? Just curious.

I haven't but one of my referrals has.

Never. But I'm wondering how I could manage such a sale with other sites (i'm not a DT exclusive photographer)

you have to remove that image from all other stock sites if you sell the right on DT. It's in the T&C's.

And you have 72 hours to do that, so it could be a problem if you, for example, are in holydays

I recently had a request with an e-mail from FT for buying the rights to one of my images it hadn't been downloaded anywhere despite being online for a whole year so it seemed like a good idea.

I set about deleting it from the other sites and making it exclusive and set the buy out option and price but so far the client hasn't bought it despite asking for a reduction in the price.