The damage issue is interesting. Most C&R regs. call for single, barbless, baitless hooks, which means no treble hooks. I'd like to hear more regarding the argument that treble hooks cause less damage than Siwash.

I use Siwash simply because I use hardware the most on nates and regs. require single barbless during the spring when most nates show up (at least on the Skykomish). My success rate at landing fish is high enough for me. Generally the steelhead slam it so hard that the fish isn't going anywhere unless it snaps your line. Hatch brats don't seem to be as receptive to hardware so I rarely break them out during the winter.

I do know a couple of spooners who have considerable experience and success using hardware for summer run who prefer trebles to single. Say they hold better. They also say get very high quality and large enough treble hooks because steelhead can straighten out ones that are cheap and/or undersized (which come with most hardware).