What do you all think?
The DIO-96 has static digital I/O. It is software timed and you would find it very difficult, if not impossible to emulate the required timing in software.
I suspect that the MOXA would work fine with LabVIEW. As long as it's drivers installs ports that windows will see as addtional com ports, there's usually not a problem. Sometimes, you can request an evaluation unit or one contingent on it working with LabVIEW.
To make the MOXA completely automatic, wouldn't you have to build a switch board anyway? There would certainly be less switches required than option 3 though. Option 3 would be done with a custom board connected to each of the 16 ports and each board would mux to 16 different devices?
I think you'll have to find out the price of the MOXA and compare it to building multiple switch boards. I don't have the information near me right now, but one of the people that used to work with me designed an 8x10 switch matrix with USB control. I think the cost per board was well under $200.