Expand RAID10 array or create separate array

Hi all,

The server I look after is beginning to get low on storage so we need to look at possible solutions. We predict the space will run out in around 6-8 months. This has accelerated due to Covid (more scanning and large PDFs being e-mailed around)
 
  The current setup:

• Dell PowerEdge T430 (PERC H730 Controller)
  • Host running HyperV & Windows Server 2012 R2
  • 14 x HDD bays in use
    • 8 are used in a RAID10 Array which holds are Server VM's (DB Server, File Server, Exchange & WSUS)
    • 2 x spare bays not currently in use

The RAID10 array has 8 x 1.2TB disks, so the way we see it currently is that we have 2 possible solutions:

• Install 2 x matching 1.2TB disks and expand the RAID10 array and then assign that space to the server VM's that require more space
  • 1.2TB of additional Storage
  • This would probably give us 2 years before filling again
• Install 2 x 2.4TB disks and keep them separate from the RAID10 array, and then move things out of the RAID10 array to this partition to free up space.
  • 2.4TB additional storage
  • This would probably give us around 3.5-5 years' worth of space at our current rate of fill, but not be able to use the hot spare.

 
Has anyone had any experience with expanding their RAID10 array and know of any issues / risks we might encounter?
 
I work remotely from the office(6 hour journey each way) so wouldn't be able to keep going back and forth for changes, we'd need to be able to do the upgrade during one visit and be confident that it will work moving forward.
 
The server is under gold warranty and I have discussed this with a pre-sales tech, but just wondering what the communities thoughts are.
 
Thanks for any time spent replying to this,
Dan