new-windows-2012r2-server-with-hyper V small office

I'm redoing my SBS2003 server.  I have a Dell R710 48g with dual Xeon x5680 processors (I know massive overkill but what the hell :-) ).  I'm planning on using Server 2012 R2 Hyper V and run 2012 R2 Std as a guest VM to run a large application that doesn't support Essentials.  That VM will run the usual print and file services etc needed for the office applications.  I then plan to run a VM of 2012 R2 with Essentials Experience role enabled to use all the management wizards etc for the network.  It will be the DC/DNS/DHCP just like SBS was.  I believe I saw this setup in a Microsoft Virtual Academy course.  By doing so I will be able to have easy administration for the 10 user network and my backups and replication should be pretty straightforward .  I have a couple of questions about this configuration:  First is this a reasonable setup from a complexity perspective.  Second, I was planning to use mirrored 73 gig SAS drives for the Hyper V host and then either a Raid 5 array with approx 300 gig SAS for the guests or a raid 10 with the same capacity.  The total data needs for the apps are only about 30 gigs at present with a slow growth rate.