When I first got interested in suppressors, a dealer recommended that I buy a stainless steel rimfire suppressor because it would handle the higher velocity rimfire rounds. Since my only rimfires were .22 LR, I decided to go with an aluminum mono core suppressor, specifically, the Innovative Arms Apex.
Now, I like my Apex a lot. You hardly notice the weight and it sounds as good as a friend's "big name" rimfire can. One of my "hosts" is a S&W 15-22 and it makes that rifle a lot of fun to shoot.
That said, there are some really good rimfire cans on the market now with stainless construction and a K-baffle design, which reduces the "first round pop". The Dead Air Mask, the Ruger Silent-SR and the Rugged Suppressors Oculus are just a few examples, and they are not terribly heavy. I would consider these as well.