Do you think the damp chaser is adequate, or preferred, or do you use instead, or in addition, a whole house system?
Either is much better than what I think most people with pianos do, which is nothing. And BTW there is a third way, which I think is more common than either of the ones you said: individual humidifier units for the room or area where the piano is.
I think most experts would say that whole-house humidification is best, but that the Damppchaser is darn good, and that area humidification is very good too if you do it conscientiously and well, which is sometimes very hard. I personally am not a fan of the Damppchaser, although it's been recommended by several techs, because of the possible bad hazards (although I've been told they are rare) and because of the related thing that I just can't get comfortable with the idea of drilling holes in the piano and putting what amounts to a tub of water against its bottom. Anyway, while most experts love the Damppchaser, the consensus does seem to be that it doesn't keep the humidity as constant as a whole-house system and that the latter is preferable in other ways too. The trouble with whole-house, of course, is that it's much more elaborate to put in, but if your house already has it or if you're OK with doing it, you're in great shape.
This has been discussed many times on the site but mostly in a different section, Piano Forum. I was in some of those discussions when I first came to the site and haven't looked since then because I found out what I wanted to, but I'm sure there have continued to be discussions there. If you don't get enough answers here, you might want to look over there and perhaps do a search -- or maybe just repeat your post on that forum, because I think more of the people who really know about this are on there.