Depending on your color combo, the Audi S5 interior ain't that bad at all. Mileage would be somewhat identical. Another option for you would be the C63 AMG but be ready to change your rear tires every 5,000 miles.
If the M3 was on your mind for such a long time, I say just go for it. You'd end up with buyers remorse if you strayed elsewhere. When you sat in that G35, I'm sure a part of you wished it was an E46 M3 instead. "Just do it!"
