To classify trance on its own with all its divisions is not a smart move when
labeling as underground or not.
We had an endless 4-page long debate over underground and its
definition, and to put it out there: no it's not underground. If anything, it's
far from it and gets further from it literally everyday.
It's mainstream, easy to get hold of, appeals to the masses, and very well
advertised and marketed.
To quote Jad: do the math.
And for further reference, check this topic if you've a free half-an-hour
on your hands:
http://www.trancehits.com/viewtopic.php?t=6290P.L.U.R.