Another thing is that aluminum arrows fit a narrower range of draw weight/draw length parameters. You choose a 28" aluminum and it shoots well. Jack up the poundage 5# and you probably need to change to a stiffer arrow. Carbons may allow you to change draw weight by 10-20 lbs and still work. With carbon you don't need to own an arrow straightener.

Spine deviation is an issue with carbon, but is still acceptable for most situations. At least it's good still better than most of us can shoot anyway.