hard disk upgrade from 2x1Tb to 2x2Tb

Hi folks
I've been reading a lot about this on the forum and ideally it should be a lot easier, but it's not !!
I think I have a cunning plan but wanted to run past the forum for a sense check.
I use my Stora in a very simplistic fashion, i.e.
- desktop mirror application to backup my PC files to the Stora
- AllwaysSync to copy my lossless music copies to Stora (for Sonos)

My thinking is:
- remove 2 1Tb disks and put somewhere safe
- install new 2Tb in slot 1 and let Stora set it up
- run desktop mirror to back up PC to Stora
- run AllwaysSync to copy music files to Stora
- install second 2Tb disk in slot 2 and setup as Raid1, let Stora sync the disks

is that me back at where I was?

couple of questions?
- Should I really still copy files of Stora to another disk for additional safety?
- would I be better/quicker to install 2nd disk as RAID1 when disk 1 is empty, rather than when disk1 is fully copied (approx 800gb)?
- I am also assumng that user settings are not impacted by this?

Thanks in advance
Stephen