Getting back to the original question about NBN over HFC…
We were moved from ADSL to NBN over HFC just on a year ago.
The speed is pretty much what we pay for - we are on a 12/1 plan and I get 11/.8 or similar - no problem there as it was faster than our ADSL that never got above 1.5 due to our distance from exchange.
But in that time, we have had 4 significant (2 hour +) outages directly related to the HFC technology, which in our area is Foxtel TV cabling. This included an entire weekend (midday friday to monday) when we had no NBN and no home phone either.
Of note, the Customer Service Guarantee doesn’t apply to home phone delivered over NBN, however it is delivered.
In the 10 or so years on ADSL we only ever had 1 outage when something happened at the exchange, and that took out dial-tone out too.