I’m now have a fibre NBN connection, and while it may just be the placebo effect, it certainly feels a lot faster. I regret not doing a speed test with the old connection, but here they are for this hookup:

Via LAN (Tully): 534 Mbps down, 46.6 Mbps up
Via Wifi (Stark): 454 Mbps down, 46.6 Mbps up

This is using Kagi’s Internet speed test, running it 3 times for each transmission medium, and taking the highest result. The average down was about 480 Mbps, with a variance of about 50 Mbps either side of the average. The up was pretty consistent at around 46 Mbps, suggesting that’s pretty close to the plan speed. It seems like the down speeds could be faster on Stark — my main desktop — it wasn’t for the Wifi, but I can live with that.

So yes, quite a noticeable improvement.