I tried it once. I made a character who's story was after each death, he'd resurrect as a random AT with random powers chosen. Ever try to take an Empathy/DP Defender through the Hollows solo? Gets tricky. If I remember correctly, I was on the 6th or 7th rebirth, had made it into Talos and got ganked by Freakshow in a mission and had enough. Never revisited that character again. Neat concept, but can get annoying fast. However, if it's a challenge you're looking for, may I suggest what I did: No START vendor powers, never team, not in a SG so no base portals, when you die you reroll with a random AT and random powersets. It's how I learned how to run the Atlas arcs faster than a DFB and get the badges plus some merit rewards.