actually, sts9 used to be VERY cool with this. i taped numerous shows in the 99>2002 era with onstage mics with fantastic results. this was when they were using regular wedge monitors, and no laptops or other fancy electronics.
they were funkier then too - hunter played his guitar more, now he likes to play computer games on his laptop for a crowd
no but in all seriousness, not only do they have a lot of instruments now which are midi or go line out to the sbd/PA, but they also use in-ear-monitors now, which makes the stage mix very different than that of a stage mix with real monitors.
so even if they'd let you, you wouldn't make the best recording. alas, they won't let you anyway so i wouldn't bother trying. just get up in the sweet FOB/DFC spot and pull a recording
best of luck!