please don't :D Using CoronaLights is much more recommended ;)
It's more recommended to use coronaLights but what are the "real" drawbacks in using the standard lights? I mean speed-wise or something like that. I would guess that standard lights with sharp shadows should render faster than little CoronaLights. If it enables us to do specific things (which are not doable with coronaLights) then it should be working well (and we should know the problem cases) ;)
They will always give you incorrect (point) reflections in glossy surfaces, the rendertime goes up with the amount of lights (but not noise amount per pass, so it is similar to the way mental ray works), and it is very easy to create some possibly unnecessary fake effect, like incorrect decay, resulting in bad looking images.
proportions between, for example, skylight and light bulbs
need downlaod alfa5 and reinstall? or this in day update?