@nicsand,

I will chime in for one specific thing, that may not even affect you, unless you are trying to absolutely maximize your connection - and it depends on your hardware / ISP settings. However, overall, you should not experience any problems, and your setup should have no problems.

T-Mobile 5G Internet tends to use a different MTU size for their data, this means that they may try to send more data per packet than your router/deco is expecting. The ability to change the MTU size is something that has been added to more recent models via a firmware update. 

The feature to change the MTU size that your Deco network expects is only required on the main node, meaning upgrading your main node to a model that supports the feature will add the feature to your entire network.