I wouldn’t ever allow Amazon to regrade and sell even though my items are low value generally. I recall them if they go unfulfillable and often there is absolutely nothing wrong with them. Equally though they sometimes put items back to stock that I’d prefer to be made unfulfillable so its not always smooth but you have to decide the best overall option for yourself as each seller needs to seriously consider this for their products.

As Stuart said, you could really come unstuck with a high value product - but even if its low value, say a £20 item that costs you say £10 - you might get this back and be able to send back in and get your £20 - or Amazon will resell for say £5. If in doubt, don’t do it. If enrolled in this we don’t really know how this works in Amazon and if enrolled you might find more items being resold than refurbished.