of course I am now more likely to run people over as I stare at the speedo instead of concentrating on driving!!!
Not the first time I've read this in this thread (and others). I really really really hope you guys are joking!
The idea that people in our age group and levels of experience cannot drive in a 20 or 30 mph limit without having to constantly check the speedo to the extent you are unable properly to monitor other road conditions is more than a bit worrying - especially for those of us who have done a speed awareness course and have been taught the correct scan sequence

If one really can't drive along at or just below 30mph without drifting up and over the limit, then one can simply adjust the speed downwards to give a larger margin of safety. It's a limit, not a target after all, and it really isn't much of a hardship to drive at 15 or 25 rather than 20 or 30 in built-up areas.
I'm as much a fan of hooning around as anyone, but deserted NSL roads away from civilisation are the place to do this, not in the middle of a town, or indeed on routes like the NC500 where there seems to be a high density of nobheads putting everyone in danger.