I would throw the 3T offerings into the hat as well but they are not flat top. I have an alu Rotundo bar and I love that thing. If you're looking for ergo, their bars are the only ergo ones I've ever tolerated.

I don't think I could justify the price difference just for a tiny bit more dampening. I ride a CAAD9 and have all aluminum parts - from seatpost to stem and bars. The vibration is something you deal with for a stiff and agile frame. I would just deal with it until you do upgrade to a carbon bike.