I have a mix of Dell R710 systems and HP BL460c G7 blades in the same cluster. They happen to have the same CPU (X5670) and the same memory (96GB). All have 10g connectivity. We've had no problems whatsoever (except that the Dells are a piece of crap to work on, even for the field service folks). We have the same shared (NFS) shared storage presented to both.
The one thing you have to be careful of in your environment is if you have a guest that actually needs 10g connectivity - you'll want to do some host affinity DRS rules to make sure you don't inflict pain on your customers if the guest vMotions to a Dell host.
We do have separate baselines in Update Manager as somebody else suggested.