A micro-adjustable seatpost makes more difference than you might think. If you can get the saddle tilt you want without it, great; but unless you have a tensioned leather or uncovered carbon saddle, as it wears in, odds are it will compress unevenly, and micro-adjustability may let you get more life out of your saddle. You can shim a splined seatpost - I do - but the shims compress, too, and it needs to be re-done periodically.

I'd be surprised if there were really a noticeable ride difference between carbon and aluminum, although I've never ridden carbon, so I can't say from personal experience.

Carbon seatposts can be a PITA - I know how easily it scratches because the one that came on my bike is carbon-wrapped. And I've read that carbon has a tendency to slip in the seat tube, and you need a special carbon paste to lubricate it. But that latter is hearsay only.

Still, I'd be hesitant to give up the micro-adjustability. (Trade ya? )