I generally don't use rivets at all in load-bearing locations. I lost a mast and two sails once and I suspect it started when two rivets broke.

That said, aluminum rivets are perfectly appropriate in other locations. The Isotope mast base casting is attached to the mast extrusion with aluminum rivets. Should I accidentally drop the mast while stepping or unstepping, the rivets shear and the casting breaks free without damaging the extrusion. If stainless steel rivets or screws were used, they'd tear out and cause far more damage than 4 broken rivets.

Regards,
Eric