I'd just have Don make you another identical cab (assuming you dig the tone) and stack them. You would get more low end, more volume, more open tone with the Thunderfunk running at 4ohms, and it will be 'higher' for you. Less money, and a higher stack than buying a 2 x 112 rig.
That being said, if your main context is backline with big front of house support (i.e., your amp as a personal monitor), just put it up on a stand and be done with it. You will lose a touch of actual low end due to a combination of 'uncoupling from the floor' and primarily due to changing the 'boundary conditions' by getting the cab a couple feet off the floor, and the cab will also increase in 'perceived midrange response' due to the more directional mids being closer to your ear in a higher ratio than the more omni-directional lows, but you can get used to that, and EQ the cab to sound like you like it.
If you decide on wanting a taller single cab, IMO, the Genz Benz NeoX212(II) is a good choice. Nice match with the Thunderfunk, lightweight, tall profile (in-line 12's), and available from Musician's Friend or through TB supporting 'Rocket Music' (great retailer, good prices). Nice sounding cab, and a good match with that amp if you are looking for a nice, warm, articulate tone, and don't need to rattle the rafters with deep low end.
Last edited by KJung : 12-04-2012 at 04:41 AM.