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
You're not transferring data, you're downloading and validating it. The later being very resource heavy.
And with lots of read/write operation rather than sequence copy.
I'm seriously considering getting my coins out of the wallet when I'm synced
That would be a waste: once synced, you'll never have to go through this again. Just keep Bitcoin Core running and it downloads 6 blocks per hour to remain fully synced.
And at most, you just need to download 360MB (2.5MB x 144) of blocks everyday. I'm sure it's small size for you since you could download about 150GB in a day (blockchain size in January 2018)