While looking for price / cost information of the Dell Equallogic storage I found this website at www.4equallogic.com
It has as interesting posting on when to use SATA drives and when to use SAS drives in Equallogic storage.
Rule of thumb?
If your IOPS are more than 600 or so, you might want to consider a SAS unit. If it’s under this, you might be better off staying with a SATA unit.
The site also has a link to a site where automatically quotes can be obtained for Equallogic storage. Mind an email address has to be filled in and gmail.com or .nl or probably other domains outside the USA are not accepted.