Not an HVAC professional but if you want to achieve humidification beyond 400ish sq.ft., then you need a HVAC whole house system. I put in a AprilAir 600 system. Took me about an hour to install and you don't need a contractor to do it.
I have used the Skutte bypass humidifier on 2 houses. Yes they work, but they are a maintenance headache. There is a turning drum covered with a porous foam that turns in a pan of water, and air is transferred between the supply and return air. Water level in the pan is controlled by a float, and a humidistat controls the unit. Since this is a cold water type, keeping everything clean prevents mold. And for me, cleaning was often since I'm on well water, but all water has minerals. TO me it proved too much of a headache to keep it clean. Maybe a steam type would be better, but I have no experience with those.
