But it raises a question for me, why is syncing so hard on the HD? Blockchain is about 250G, that's only a few minutes for a SATA6 drive
Sequential reads and writes are not important. You should be more concerned about input/output operations per second (IOPS). HDDs usually reach ~75 IOPS while SATA III SSDs can go up to 120000 IOPS or more. NVMe SSDs are even better in this aspect.