Mobow pretty much said everything I would have. If you are happy with the arrows you have and they tune well I would suggest sticking with them just to negate any headaches. Unless you like tinkering. Sometimes it's hard finding the correct spine for a set up, once you do I would leave well enough alone.

I have shot both aluminums and carbons and will be honest and say I have never had any trouble with either. Aluminums do have better tolerances compared to averaged priced carbons but most don't shoot well enough to notice the difference really. My favorite carbons are Arrow Dynamics Nitro Stingers. They shoot fixed blades very well for me and they are SO stiff spine really isn't an issue anymore. These are a tapered carbon arrow with a fair amount of FOC built into them.

That being said I shoot aluminum arrows now, as does my girlfriend. In my opinion they are just better arrows for the money and they are easier to work with for me. With proper care aluminums should last just as long as carbons do. At least they do for me. I have never damaged an aluminum arrow in a way that would not have also damaged a carbon. The upside is with the aluminum you can tell you damaged it. If you smack a metal arrow with another one it will dent it or put a crease in it. This will not happen with a carbon. Does that mean there is nothing wrong with the carbon. Nope, it could still be damaged inside messing up how straight it is, the spine and the safety. There are pics floating around here of people with carbon arrows stuck in their bow hand. Most likely this is what caused it. They had a damaged arrow and didn't know it.

Again, most of it is just opinions. Pretty much any arrow on the market today will work well as long as it fits the bow. Under spined arrows can be hard to tune with fixed heads, so it is usually a good idea to pick an arrow on the stiff side of the scale. That is another advantage to aluminum now that I think of it. There is a much wider choice of spine than with most carbons.

*** EDIT***

Arthur posted the same time I did, after reading his post I would like to say ditto to everything he said and I would like to add I am at the other end of the spectrum, I shoot 25-26 inch arrows most of the time. Short arrows show less differences in tolerances compared to longer ones. This might be why I don't notice a big difference between the two types of arrows. Also if you shoot a lot and have decent form with target tipped arrows you can get away with a lot and still shoot well. Target arrows are pretty forgiving, put a fixed blade on that sucker though and look out!

I also shoot thin walled arrows. I shoot 2213's and my girlfriend shoots 1713 platinum target arrows. These are pretty fragile arrows and the only time I damage one is if I mess up and miss or strike one with another arrow at closer ranges. I will also add that I rarely shoot 3-D, but when I do I actually like aluminums because they pull easier for me.

Paul