FTTP with TP Link Deco M9

[#1]

Sorry if this sounds a naive question but is there any benefit in using the Plusnet Hub 2 router with a mesh network (I will use Deco M9s) or is it best to use the first Mesh node plugged directly into the Open Reach ONT?

I'm due to go live in 2 weeks and have been using Decos for some time so would prefer to carry on if possible - is that likely to cause any difficulty? Is anyone using a similar system (TP Link or other)? 

Finally, in view of the fact that the Hub 2 is effectively the BT Smart Hub 2 (I believe) would I be better buying the BT Premium Whole Home WiFi system rather than using Deco M9s (would all being part of the same group offer any advantages)?

Are Plusnet thinking of introducing something similar?

OK that last bit was a bit hopeful, I doubt that Plusnet will be offering any add-ons to their basic FTTP.

[#2]

Hi
Rather than buy new equiment, I would use the Decos in router mode with one hardwired to the ONT.
You will need to setup the login to PPPoE to Plusnet.
You can obtain your username and password from the Plusnet member centre.
The Deco setup procedure using the smartphone App should guide you through the process.
Regards
Richard