G'day Sean,
I agree it can be a bit frustrating selling solutions to customers if they are not strictly on the HCL.
However, perhaps Open-E can help here.
Since iSCSI and/or NAS are the protocols involved.

Tom, can Open-E provide a statement that would confirm that Open-E DSS conforms to the ESX VMFS requirements, regardless of the underlying hardware?

What I mean is, if when using iSCSI for example that there is no difference to ESX, regardless of whether you are using SAS or SATA, or a particular Raid Controller.
Therefore, so long as the Hardware is certified by Open-E for use with DSS, then we as integrators can be confident that it will work. In particular I am thinking of the drama around the SCSI RESERVE and RELEASE commands.

(Forgive me if the iSCSI protocol does not work this way, as I am not as familiar with it as other protocols)

I know that will not satisfy all clients, but it would give me the confidence to try to sell it to them. Particularly if I can convince them to try DSS-Lite in their Test environments first.

Rgds Ben