Concerns are always valid, but there is a level at which you have to bite the bullet and take the plunge. I am not an expert, but I suspect the coil whine goes away with hours/time on the device, which people are sending it back after the first hint of noise and no one has any data to support or refute my supposition. Personally, I would order a refurb, pull it out, set it up minimally and run a Unix process or looping Cinebench to see if the coil whine stays or goes or if it’s even present. Something to stress test the device as much as possible before putting it into production. Slam it hard and it either performs or it doesn’t. Hopefully, that answers your questions/concerns.