Aluminum and carbon together oxidize. If it's in the head, it's a really bad idea, but a carbon tail in aluminum tubes? Not sure. The original Gulf Tech booms had a carbon body and aluminum tails, but they also transitioned away to all carbon. I think the stiffness is generally considered to be a boom body issue and not a tail issue, so carbon tails don't sound like a worthwhile idea to me.
In time carbon fatigue will surface. I have had two 100% carbon booms break at the head, but only after several years of use. On the other hand, carbon will most likely last much longer than aluminum.
And if you consider that you could possibly replace your aluminum booms every other year and spend less money than replacing your carbon booms once every 6-8 years, aluminum doesn't sound like a bad idea, especially if you are a fresh water sailor and use the booms on medium to small sails.
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.