@Andrasd 

Hey

In terms of range, generally, this isnt affected all that much between Deco devices as its a limitation of the antenna itself.   Yes the larger more expensive Deco (like the x90) will have slightly larger antenna which offers a marginal increase in range, but honestly its 10% at most.   Sadly its a case of diminishing returns as you increase antenna size, generally you find most APs are roughly the same range.   What does make a difference is the banding, the X90 is a Tri-Band so therefore can give you 3 connections at once therefore increasing speed, think about this like a 3 lane motorway vs a 1 lane, its not longer, but can carry more traffic so is "faster" overall. 

OK so the x90 has a 30db antenna for 5ghz and 20db for 2.4ghz.   In short this is as high as you can transmit, so there is unlikely to be any Deco that will make much difference.

Integrating into the existing, not an issue..   Just open the app and choose the ADD button (top + on right) then add new deco node.    Walk through and it will detect and add the next node as you need.   Job done, easy :)

  @Philbert 

Thank you!