Plain and simple, I'm afraid, Brian The Dog (is that you Wave?) is wrong and Thine and D123 are correct.
This whole problem has come about because LTE was rolled out with no voice.
Up till now all networks have rolled out 2600, 1800 (and in the case of VO2) 800 running at a lower power than their respective 3G coverage. To always allow an underlying CS network for voice.
This all purely due to someone's stupidity in releasing LTE with no voice. I mean... DUH!!!
It's no good blaming Three for this. Both Three and EE have the same issue.
Both Three and EE will have to only allow 800 to specific handsets that can do 800, have VoLTE capability and have the relevant firmware installed.
VO2 can allow it to everyone.
ThrEE can run theirs at full power and therefore eventually will have the best coverage.
VO2 have crippled themselves as they can only run their 800 within 3G900 or 2G900 (eventually) for the foreseeable future.
At the end of the day Mr Wonk ( I just love that!) is correct, the general public have no bloody idea what is going on. They will eventually just see better coverage. They will have no idea why that is. They won't know it's because their phone has 800 and VoLTE capability, they won't care.
They will just go "oh, I can get reception here now, that's cool, I'll think I'll stay with this network...."
You have to remember, we on here know what is going down.. MAN!!

. Most of the walking dead just trudge through life and any attempt to educate them to the new technological advances is normally met with a very blank expression.
Bottom line?, you can argue about Three's plan of releasing 800 on a lower priority then 3G and that's a fine argument, but don't blame Three for the whole 800/handset issue. Not their fault. Out of their control.
If you want to blame anyone, blame Google...