This thread is about where clogs come from and the z3100 and 8300 are not immune to them at all. It just handles them with a different technology so they're not in your face. If you live in a dry climate and use your printer rarely you probably have hundreds of clogged nozzles, and your heads will eventually "fail", because that's what they are designed to do. If you own a Canon those new heads will be pretty pricey. HP's are a little more reasonable, and they have the advantage of not having to replace half of the colors but just two at a time, meaning the failures will be more gradual and easier on the cash flow.
Head failures haven't been a significant issue with Canon's so far because they have been on a pretty aggressive upgrade path since the initial ipf5000, and so a great many have upgraded before wearing out the heads of their current printer(I have 2 myself gathering dust, and both would require 2 replacement heads to get up and running again, not worth it). This may change since it seems we're at a point now where it may be difficult to squeeze much more quality out of these printers so people will own them and run them longer.
This thread isn't about whose technology is better, I think both have advantages and disadvantages. It's about the fact that ALL pigment ink printers clog, and there are things you can do to perhaps make it less of an issue. (i'm going on 8 weeks with a 4900 and 9900 used only a couple of times a week without a single clog. I'm probably gonna turn the auto nozzle detect back on because it's getting to be a waste of time to run manual nozzle checks. Just from an automatic humidity control system).
Keeping the humidity controlled for a Canon or HP will still be of great benefit, as it will most likely add a substantial amount of time to the life of your head. and I agree, I think the Canon experience in this area is equal to the HP. The 3100 is older technology, and the 8300 offers a substantial benefit in output quality that in some areas will be obvious. Not that the 3100 is bad (although I never felt it did very well with reds).