Since grid output stats make no distinction between a var region and an ordinary region I would just report the total number of regions as usual (I'm doing that with my own search engine). There has never been a need to state how many mega regions on a grid because they all consist of standard 256X256 regions so why try to do something different with var regions? Leave it up to the grid owners to say whether they support var regions, or scenic regions or mega regions or any other kind of region. It's just not worth making Opensim look like a joke on this issue when reporting metrics.
To my mind var regions are very useful for role play, sailing, etc, etc so lets not get carried away boasting about the area they create. Usage numbers are far more useful but I would say the growth trend is more telling still. Remember, Maria lets us know how many grids appear to be gone every month and usually a few new ones come on line. That's far more helpful to know.