I just bought the Rebel 17 from stainlesstumblingmedia.com. I had used a conventional tumbler up until now. Here's my $.02.
The conventional tumbler is quicker to use and works just fine. However, if you have old grungy brass that was picked up at the range or you want to remove the tasks of cleaning primer pockets from your loading process, stainless tumbling is the way to go. It's somewhat more cumbersome to separate brass from media in that you also have to deal with water. In saying all of this, I'm extremely impressed.
I'll continue to use the conventional tumbler for my long range loads as I feel the SS tumbler gets necks too clean and can create tension/cold weld issues. However, for a first cleaning on old brass, it's the way to go.
