As far as I'm aware in Windows Server 2012 R2 you can configure Storage Spaces to have two tiers and it'll migrate data between them automatically. These tiers are called 'SSD' and 'HDD' and are meant to utilise those disk types.
My question is can you 'lie' to it about these and assign a disk pool of 15krpm HDD's to the 'SSD' tier and 7.2krpm HDD's to the 'HDD' tier - or does it somehow check this? I can't test this in our labs right now as the hardware hasn't arrived just yet sorry.
AFAIK you can run storage spaces even from within a HyperV virtual guest so I imagine yes.
Use the Set-PhysicalDisk commandlet to set the media type which appears as nothing more than a label (and not an actual physical property):
And simply add all disks labeled as SSD to one tier and all disks labeled as HDD to your other tier.
http://blogs.technet.com/b/josebda/archive/2013/08/28/step-by-step-for-storage-spaces-tiering-in-windows-server-2012-r2.aspx