We installed a Tornado in our ROO HTT and it did a find job. Always, always add about 5 gallons of water and chemicals, if you wish, to the tank after dumping. If you've missed anything, that amount of water will keep it from turning to concrete. Our new TT has a black tank flush hookup and DH has said he likes it a lot - saves crawling around on the ground to hook up the Tornado.
We've been using Odorlos for a few years and have been pleased with it, but have been contemplating the Geo Method. Easy enough and more economical than the Odorlos. We're going to be out of Odorlos before the end of the season, so the test will be coming soon. Sensors are notoriously inaccurate, but those using the Geo say that it helps keep them cleaner and more accurate. That would be a great benefit. Two, maybe 3 trips from now, we'll have an opinion.