Whew....I bowed out of the discussion only to find plenty to weigh in behind me, so I guess I'll join in the crowd. Sorry George, the whippersnapper in me just couldn't stand it :D
I think Ray hit the alum #'ing change square on the head: while it may be a marketing issue in part, it also makes plain sense to cut down the 50 spines to 5...cause tuning will get you there with those "limited" choices. I know...it's not the "old school way" of doing it, but it's sure hard to argue the results.
I prefer carbon for multiple reasons and think it is a superior material. I seldom say "superior" and usually talk about opinion...but in this case I feel confident in using "superior".
Durability: Someone said something like, if polled, I'll bet carbons would be called more durable by 10/1. I don't doubt that, even if factoring in the greater number of carbon users. I used to shoot alum out of my compounds and didn't stump shoot because of durability issues. I did try alums but also discovered the joy of stumping...way more bent alums in my back yard than busted carbons. Went to a shoot that forbade carbons...I was smokin hot that day and way ahead. I lost some of my lead on 2 bad targets that I thought were my fault until I noticed very poor arrow flight on the 3rd. Someone bent my arrow while pulling (2314). I used a straight arrow for the next target and smoked it...checked the arrow and it was bent. From that point on, no-one pulled my aluminum arrows but me. Carbon is either straight or broke.
Flexibility: Taking my 64# morrison as an example, I can build arrows that weigh roughly 450gr to 850gr, all using the same 200gr head, that fly perfectly so I find them far more flexible.
Weight: As far as weighting etc., I personally think Dr. Ashby has enough data to convince me high FOC improves penetration. I think it's much easier to find an appropriate carbon shaft for high foc (and still make your target arrow weight) than it is aluminum...and I believe carbons recover faster from paradox making high FOC more viable with this material. Look at the weighting choices for carbons as options, not detriments. Another option: want to shoot a light arrow for 3d and heavier for game but don't want seperate arrows...tube em; can't do that with aluminum.
I don't agree with "the weights I want" type statements either: I'll bet I could build a carbon arrow (within reasonable range) within 10 grains of what you want your target weight to be. The sheer # of carbon arrows produced in weights from 4gr/in to 15gr/in cuts a wide swath. There is a carbon out there for everyone.
Straightness: Yes, aluminum are minutely more straight than carbon only shafts. But, most carbons aren't far off: this is a common misconception regarding carbons. Most of the runout I have found comes from the ends of carbons. When cutting, try cutting equally from both ends...some of your runout will disappear. With this method, and using the Arrow Squaring Device on BOTH ends while building the arrow, I find them straighter by far than I can tell in shooting. With trad gear and 99% of the shooters out there, I think even the poor end of the spectrum of .006 is simply overkill (most of the better carbons I measured when I got curious came in around .003-4).
Aluminum certainly isn't dead and gone, for that matter I hope none of the arrow materials leave us; the more choices the better, imho. But purely based on "performance", I am convinced it's tied for second at best with wood. Choose wood or aluminum because you like them better....but I don't think you could prove they are superior in any fashion.
There, the gauntlet is down...and it's made of carbon