You should be pushing dehumidifiers where they are really needed like damp musty crawlspaces or houses with poor HVAC systems where it is more economical to add a dehu than to rip open walls and ceilings to replace the duct work.
If someone truly wants that steady non stop fresh air the erv is the way to go, and with a tight home a small inexpensive 40 pint dehumidifers are going to remove all the moisture in 'shoulder seasons'
Intermittent exhausts are not problematic until you get into the magnitude of Jenn Air grilles, stainless steel hoods. In that case the 50 CFM brought in by an over priced thermastor dehumidifer is going to be very insignificant.
With a tight home the original poster should be looking at the combustion appliances to be all sealed combustion and directly vented and it is wrong to even suggest a little bit of ventialtion air is even sufficient for combustion purposes.