We have been using EU-ETS for many years now, it has been so reliable that I would not want to go back to doing all of my ticketing manually! This is because it's very easy to use, and you don't need any training at all. There are plenty of tutorials on their website, and you can find help in the forum and support teams if you get stuck at any point. It takes a little time to understand how everything works, but once you do there is nothing stopping you from adding your own new features. You can also get a free trial version which gives you a good idea of what you're getting yourself into before making a big commitment. Tracking our carbon footprint is important, and this has allowed us to do just that.