I've only done 2 HPDE events so technically I'm still in level 1 (green). however this weekend I attended an open track @ Pocono, which makes 3 events total now, and was running wheel to wheel with group 3 & 4 driver in their all out race cars, man what an experience that was.
OP, I noticed you are torn between an sk2 & EVO, you really can't make a bad choice for either car, both are very very capable platforms for what you intend to do. I would recommend an EVO though as its a little more versital but I'm biased because I own one.
EDIT: Jim, what happened to you this weekend?