So I found an Eleven Rack for $150 (!) 10 minutes away from me (thanks NYC!) and gave this a try today...

and it totally works!

Haven't spent enough time with this for an opinion yet, but seems pretty cool. My primary interest is in using single-amp but dual-mic (or dual-cab) setups. Its a little bit of a pain to replicate the rig on both boxes, but so far using different stock 11R IR's for left and right channels really does seem to add some depth to the overall sound, while maintaining all of the 11R's great feel.