Do you know what caused the ylod (is it a matter of replacing the thermal paste, a cracked mb, in need of a reball, power supply going out)?
I would first look into seeing if it is repairable before losing everything on it.
Do you have any extra drives laying around that you could use as an external to backup everything on the slim? Might be a bit quicker than ftp.
The first thing I would do is find out what the cause of the ylod was.
I would much rather go to my grave not needing my gun, than go there wishing I had it.