Yes also the FTTH variant is different as well. It's not a big deal really as I've never actually noticed it reboot after 14 days, I have noticed firmware updates though. BT really need to stop pushing out firmware updates at 8:30PM which last 20 minutes, and right now I get one every few weeks!
I've had no performance issues with the Smarthub in fact it's probably my favourite ISP supplied router, but I do hate how it can just update itself at a whim and BT don't even let us know what the updates do.
The updates are more frustrating than the 14 day rebooting, I know this will settle down soon as it's a new device still.
My real issue with the Billion is the wireless, I am on a top floor apartment now and 2.4Ghz maxes out around 5Mbps during every evening. I actually had turned off 2.4Ghz for around 3 months as it was that useless... There are times it just grinds to a total standstill.
I note the AC version somebody provided which would be a good solution but I'm struggling to justify over £100.
For reference here is my WiFi environment:
https://s29.postimg.org/4muucspnb/IMG_0041.jpg
I have around 20 devices connected, only one is wired the rest are 5Ghz. The routers hidden inside a built in wardrobe so probably not the best location, but the master socket is here and the only socket nearby is in the wardrobe... I also mean to change this at some point.
Thanks to the person who linked me to the BT forum as I can see a full list of supported routers on there!
I am 99% certain I will change the router, probably at next payday