I don't own a bike trailer (or jogger) myself, but I had strongly considered buying a Chariot Cougar before I spent my baby transport money on a seriously nice carseat. (It's probably best as another topic, but the Britex Marathon carseat is worth every penny!). For me a bike trailer was less important than a jogger, but the ability to convert the Cougar from a jogger to a bike trailer was a serious bonus, even though it tacked an additional $150 onto the price as compared to my next choice for a jogger (the B.O.B. Revolution).
I read a few reviews comparing the Cougar to the Revolution, and everyone who has used both prefer the Cougar because of the flexibility. I also try to talk to people that I see using the Cougar, and no one has had anything bad to say about it. I haven't met anyone that has actually used the hiking and cross-country attachments, and just about everyone has shared my skepticism about how functional they would actually be.
I just checked the Chariot website, and they have a lifetime warranty on the frame of the carrier, and a one-year warranty on the fabric and hitch. I'd be most concerned about the hitch, especially if you're changing attachments on a regular basis, but I'm guessing if there were a problem you'd see it fairly quickly. Also, REI is really good about returns, so I'd imagine you can return it after the one-year warranty if something fails.
I wish I had more practical experience for you, but figured I would help get the ball rolling.