Good advice in this thread.
I use the Thetford liquid w/formaldehyde and - in warmer weather - one Potty Toddy tablet.
This has been our first season with our 2720 we bought in March. And, the toilet was the only serious problem I encountered. See
http://www.trailmanorowners.com/foru...ead.php?t=4741 for more information, if you are interested. There was definitely a strong odor from the toilet, before I fixed this problem.
Since I fixed the problem, the toilet no longer gives off a strong smell. We are into the cooler weather now, so I'll continue to monitor this next year. Personally, I believe if Thetford's products are used as instructed, there will be minimum problems with odor.
My experience has been that using non-Thetford products, less Thetford product than instructed, and failing to fully charge the toilet when setting it up for use, will lead to unsatisfactory results. Wal-Mart seems to be a good place to save a few bucks on Thetford products, if that's what I want to do.
Happy Camping!