Hi here is my situation.

I have a 58MVC100 furnace that was installed 2.5 years ago and I wish I had known more about this stuff then because I am a bit ticked off by how it is set up.
There is a couple cheap single stage heat and cooling thermostats that are hooked up to a Honeywell Zone controller board (HZ322) and the zone dampers are connected with 2 wires (common and closed).

I had an HVAC guy come in to quote me a humidifier and what I am learning now is that the capabilities of my 58MVC are being wasted by this setup. The ideal situation would be to switch out the controller and stats to use the Infinity controller and slaves which also means replacing the zone dampers with 3 wire (power open and close). However doing all this is quite a bit more than I had hoped to spend.

Another alternative, I had thought about is go ahead with the humidifier but upgrade my thermostats to ones that could do 2 stage heat as well as humidity control like the nest (yes there are enough wires). Going this route is quite a bit less.

I would love some thoughts as to my dilemma. Would I get back my investment if I go with the Infinity? How much better is that than my other alternative. Staying with my current thermostats is not an option because I want the humidity to be controlled from the thermostat (don't want to be turning a dial in the garage every now and then).