I guess my question would be why such a large hook????
Most people out here use quite a bit smaller hooks than they would normally have on a standard steelhead iron. The big win with tube flys IMHO is you can fish smaller hooks which stick better in a fishes mouth than a bigger hook. I am found of the gammie octopus hooks in size 4.
I guess I would not see a reason to ever go above a 1/0 unless I was fishing for 100lb+ fish.
I have tied a few saltwater patterns for coho and cutthorat out here and the tiemco 911s in smaller sizes seemed to do the job.