Have used them extensively in Missouri.
For Colorado, I find no need as long as remember to turn the humidifier off on my furnace and exchange plenty of air in the house, which also keeps the in-house co2 lower and helps the humans and keeps the pH up in my tanks.
I just suggest a portable unit with a larger capacity reservoir. Built in ones are fine, but they are more expensive and stuff and getting the humid air into the room that they are in is not always easy, unless you are just lucky and both are the same. I found that having a unit just in the room where I needed it (sump room) was plenty fine. If that room has a drain, then great... if not, then you do have to empty a the reservoir every few days.
We usually have to add humidity to the air in the winter time with all of my tanks. We do LOTS of air exchange, though, and we run a 10k+ CFM whole house fan even in the winter time now that everybody is used to the nice, fresh air... my kids have asked me when we can get the stuffy air out during a longer cold-spell.