TH Oliver helped me choose and install Aprilaire Model 400M (manual control) whole-house humidifier.
All of my questions were promptly answered, including technical questions about installing in the system with an UV light, which required contacting the manufacturer. The price was reasonable and installation was flawless - some manufacturer-provided components were replaced with better quality ones to give additional peace of mind and the emergency drain line was also installed.
After operating the humidifier for a few weeks I've decided to set the humidity level between "30" and "35" to minimize amount of condensation on windows (I unfortunately only have double-pane windows). I use the ecobee thermostat and wish it supported both an HRV and a humidifier without custom components. Automatic operation of the humidifier to make the level more comfortable when it's not too cold outside is the only improvement I want, but the manufacturer's own automatic control wasn't too convincing. TH Oliver advised to go with manual, less expensive control while smart thermostats catch up.
Thanks again TH Oliver Team!