Hello Paul,
One consideration not mentioned is that of ride comfort vs. handling. It sounds as if your car was built/bought for road handling rather than the ride comfort. Run flat tyres are inherently firmer since they have reinforced side walls capable of withstanding loads under deflated conditions. I would recommend non run- flat tyres for 'normal ' cars, but for yours , you might wish to consider the possible effect of handling if you do move away from fun flats.
Not sure if this helps, but at least it might introduce more debate before you decide.
Kind regards,
Gareth