For anyone here who has a Teasi navigation device: the company will cease support for them at the end of December 2021. They cite the competition from phones as the reason.
You have until 31 December 2021 to update the software and maps to the latest versions.
I updated my Teasi One 3 (the pre-compass model with less memory) from Caph to Edasich. The system runs noticeably faster. I can't say if it affects battery life. Other reports on
https://gpsradler.de/ confirm my impression (in German).
You can download all the maps with the Tahuna (Teasi) software. The best way to do this is with the Teasi /not/ connected so it downloads to the computer only. If the Teasi is connected it will also put them on the device. I downloaded all the maps for the whole world. It takes a very long time as the server is quite slow.
I have also downloaded all the online documentation I can find on the Teasi / Tahuna website. Ask here if you have a question.
I plan to keep using my Teasi until the battery dies or I get fed up with powerpacks / the USB output on my Plug 2. The mapping here in Germany is excellent. I find the Teasi works well for my uses. Britain is mapped far less well in OSM, particularly footpaths. In Germany much public mapping data has been donated to OSM. You will find every building here in many places- not in Britain.
Peter Lancashire / Düsseldorf / tout terrain 5th Avenue Rohloff.