Some say a 2TB will work on a PS3, but not all do. Most people only have a 1TB or 1.5TB and not all those work.
Yes you most definitely can copy hdd0: from PS3 using Multiman mmOS file manager.
Once copied, shut down. Change hdd.
Have your Rogero CFW on a USB ready in case it asks for the update when you restart the PS3.
Reinstall Multiman once booted. Then copy the whole hdd0: back to PS3. Once done reboot and should be good.
If not, then go into recovery and do Option 3, then Option 4 is what I have done in past.