I brought my late 2012 iMac (with High Sierra and a fusion drive) into the shop for repair and they said I need a new hard drive. They will install High Sierra for me and then I can restore everything else from my Time Machine backup. Or I can tell them to just install the drive and I can install the system and files from the recovery partition and Time Machine.
Is there any advantage to letting them install the operating system or better to do it myself? Are there any special issues with a fusion drive?