So before we start, let me provide some background:

My family and I live in 2 storey house (around 260 square meters). I initially got the GWN7000 and 1 x GWN7610 access point. I'm fortunate that I have a in-wall cable run to the downstairs floor but it's not in an ideal location so couldn't use that for an AP - My router and AP lived upstairs. I have a 2degrees Ultimate Fibre plan which says promises speeds up to 900/400Mbps.

The setup initially seemed to be working well. Then the update crippled my my speeds and I was getting 250ish Mbps. I preserved thinking an update might fix this issue (almost for an entire year). During this time my wife kept complaining that there was patchy reception in the kitchen downstairs and my son's gaming rig in the living downstairs was so bad I had to put in a powerline to keep him happy. (~30Mbps) 

I then came across the UDM, researched quite a bit and took the ultimate plunge:

1 x UDM

1 x UAP-IW-HD (to connect to the in-wall cable downstairs but out of sight)

1 x UAP-FlexHD (in the living meshed to UAP-IW-HD)

1 x US-8-60W switch to manage all of physically connected iot gear and secure devices via vlans and to provide power to UAP-IW-HD downstairs

I'm currently getting 1,094 Mbps down and 481 Mbps up! I can walk outside my house in any direction for around 10 meters and still get excellent wifi. There are virtually 0 dead spots inside the house so I pat myself and crack open that cold beverage telling myself that it's money very well spent.

Yes the kid and the wife are very happy which is a bonus!

Some setting details:

- My channels are set to Auto as I've found it works best in that mode and tries to choose the channel with least interference.

- I have explicitly set the preferred backhaul for the Flex HD to be the IW-HD downstairs as sometimes it uses the UDM upstairs but IW-HD has a much better range/throughput.

- I have put every device that is not a computer, tablet or phone on an iot vlan (with a hidden wifi ssid). Lan users can talk to iot devices but the connection cannot be established the other way around.

- Setup a guest wifi with vouchers that expire after 4 hours (I know this was a geeky/showoff move to my friends but hey YOLO!) 

- Setup a vpn 

- I have enabled DPI and Threat Management and don't see any performance issues based on my throughput above

Final Remarks:

It's been 2 months since I've had this running and it's been amazing. Devices roam between APs seamlessly, the app is excellent (on ios atleast) and I can do most of what's needed in there.

I couldn't be happier!

If you have any questions regarding a similar setup you are thinking of doing or anything I can help with, feel free to ask - I'll do my best to respond.

Cheers.