When our Diaper Genie broke, we got the Champ on a friend's recommendation. I don't know what that friend was thinking. It was so GROSS! You just basically dump the diapers into a pit. It was the most disgusting thing ever to empty the Champ in the outside garbage because it did nothing to seal off the diapers. Blech! The stench was terrible after just a day or two. I actually threw out the new Champ entirely after about one week of using it. ***P.S. YES, I used a plastic bag inside. I followed directions precisely. Even put a deodorizer inside the thing to get rid of the smell, but the thing was just awful.
We use the second generation Genie and like it. We use it for a daughter who's still night-training. Much better than the first model (HATED that!) and I understand the even newer model is even better. It seals off the diapers inside, so you don't get the odor issue like the Champ. Still hate the bags and getting them to cut to empty the thing can be a hassle, but overall it does the job. For us, having a two story house makes it impractical to take every wet pull up outside immediately, esp. with bad weather.