If you copy-paste your entire configuration like @prohand did here :
You won’t lose anything, and you can switch back to HA once your test is finished if you ever want to go back to HA ^^
Afterwards, it’s a bit more technical but for now there’s no choice as long as we don’t have the feature.
If you encounter any problem when adding devices, don’t hesitate. It happens that some devices are not compatible, we don’t always support everything, but it can be added easily if you ask us 
For TTS, if it’s local on HA, that means we could integrate it the same way on Gladys. I proposed a cloud offering so that it would have a very nice voice (generated by an AI — powerful GPU needed), and for ease of use, but I’m not opposed to local options if they exist and are stable and reliable.