Thanks to many justified requests we have discussed again and will run Teamplanbuch (the previous version and the BETA) in any case until at least till the end of March. So there is enough time for you to make the change and for us to improve the new version.
Please note that the support for Teamplanbuch will be limited then. The support for Gumb will of course remain. The subscription times have already been migrated from TPB to Gumb and no more data will be migrated at the moment.
During this time we will of course continue to work on Gumb at full speed to release further improved versions as soon as possible. An overview of all features that are currently in development and will follow soon, such as the cross-group scheduler, can always be found here.