David, just a few things to consider
As Danny mentioned, setting up your NX-Otica networks for bi-amping would be simple. Buy a set of tube connectors, make a block to add to your existing c/o board. snip the pos lead going to the low pass inductor and neg wire to the neg tube conector, attach them to the new tube connectors..
There is a pretty big difference between the NX-Oticas with the extra woofers compared to the NX-Otica MTM's. I've spent significant time with both...... when originally setting up the MTM's I thought they were pretty equal. Spent a few months with them while Don borrowed the Oticas during the finishing of the NX-Tremes. When I got the Otica's back, I was really surprised at how much mid bass detail there was Those 4 extra woofers in the 80 to 200 range make a big difference.... you've got them... I'd keep them in the loop.
If you choose to go for the MTm section only you should know the MTM's use a different network setup, the mids are not high passed as they are in the full Otica's so you'd want to pull out that bundle.....you wouldn't want to be passing your filtered signal through the high pass bundle of caps for the NQ's. IIRC, there is also a different resistor value on the notch filter on the high pass filter for the tweeter (comparing the full Otica to the MTm's).
If you followed through with the ICE Power AS/2, hold off doing anything until you give this a try.... you may be surprised. I'm hoping to have one in the room here in the next week or so for some trials... will keep you posted