For a little over a year I've had naked VDSL2 with Spark, and we were getting around 38 down, 13 up. Then after a year I started getting a lot of disconnections, sometimes several an hour (and sometimes only a few a day). First we tried a replacement modem from Spark, but that didn't seem to really fix it. So the next step was for Chorus to come check things out.
They never looked on the property as far as I know, but they did drop our speed down a level at the exchange. Now we get around 24 down, 7 up.
I still get the occasional disconnection (sometimes none a day, sometimes one or two), so I'd say it's generally better. And I understand that they dropped the level of speed as perhaps the copper couldn't handle it without problems. But then again, we went a year without any troubles at the higher speed.
I wonder if there might be an issue elsewhere with our line and lowering the speed helped, but that if the actual fault was located / fixed, we could go back up to the higher speed.
If anyone has more knowledge on this sort of thing (I'm positive many people will have more knowledge than me) it'd be interesting to hear your thoughts.
Our current speed is certainly not bad, I'm much happier with it over our older ADSL2+, but it's the difference between being able to stream 4K and not.