I dont know about alu on alu, but the spike in alu rivets are often plain steel, which corrodes badly. In addition, alu rivets are not that strong. Monel rivets are both strong and pretty neutral against steel and alu. I believe monel rivets are what most riggers use, but perhaps Jimbo know something I dont about stainless rivets.

Carbon fiber rivets? Carbon really corrodes alu, and besides, it would not be very practical as carbon probably is to stiff to deform when you pull the spike.