i read in the duct tape marketing book that you could probably do without 20% of your customer base, because it's just not a good fit. that guy probably falls in the 20%, let him walk.
also, i'm not positive running 12 oz. at once through a head would do damage to the pump, but i wouldn't risk it.
If the machine has a vibe pump it could do damage, but that is really dependent on the time it is ON. If a very coarse grind is used and 12 oz. is achieved rather quickly then I'm sure it'd be fine.
Brady, so you don't think any HX is capable of maintaining decent temperatures after 12 oz. is extracted?