I had an Elise for a very short time. No issues whatsoever. It's such a simple car, I can't imagine it having very serious issues. The drivetrain/powerplant is Toyota.
That said, insurance was a bit higher than any car I've owned (though still reasonable - YMMV). This could be due to the fact that small amounts of damage to the body wind up costing astronomical amounts.
IMO an Exige S is NOT a replacement for the M3. They are so ridiculously different. They are worlds apart in practicality. I would hate to daily drive an Exige. Especially if you care about being in something safe.
It's the very definition of a toy.
2009 BMW M3 E92 6M AW/FR
Eibach Springs + H&R Front Sway + LUX AE + LCI Taillights + BMW Performance CF Spoiler + Bastuck Clubsport Exhaust