Mismatched cab question: running 2 of same exact cab, but different impedance?

[ishouldbeking]

Hola folks. I just bought a walkabout scout combo (12", 4 ohm cab) and I ordered an extension cab to go along with it... Now, the dudes at the Mesa store pretty much insisted I order an 8 ohm cab to go with the combo, so I trusted them But I'm uncertain about the logic, so I'm posing the question to you all. This amp CAN handle 2 ohm loads, as many TB'ers can attest, though the Mesa dudes recommended I run it at 2.67 to be safe.

Will there be any issue running a matching 8 ohm cab underneath a 4 ohm cab? I know the 4 ohm will be getting more juice, but will this have any kind of affect on tone other than (possibly) having slightly lower output than if I were to run it at 2 ohms. I know there's lots of talk about the tonal disadvantages of mismatching cabs, but I always thought that referred more to different speaker sizes, etc as opposed to ohms. Gracias.

[billfitzmaurice]

The 8 ohm cab will get half the power that the 4 ohm does. It's not a gigantic issue, but if the reason for adding the second cab is to get the most you can out of the rig it's not the best choice, because you won't.