I think expectations might be a bit to high here. However I may be interpreting this wrong. From what i gather from your original post is you're looking to "try" to spey cast/switch cast 6"+ big stuff, and that is going to be extremely difficult for even an experienced spey caster, with a full spey rod let alone a single hand rod. However if you're looking at single hand casting those poppers and pike flies, your rod will have no issue in doing so with Rios pike musky taper or the outbound short.
Now to answer your second question in regards to using it for salmon/steelhead.... Theres one very good line that i always recommend, and have used it on the island on a 10' 6wt for pinks and coho. Snowbee's switch line is bar none one of the best lines i've ever fished as far as roll/switch casting with tips go with a single hand rod.
http://www.snowbee.co.uk/_webedit/up...ch%20Lines.pdf
These can be purchased either from snowbee directly, or from nile creek fly shop on vancouver island. Courtney at Nile creek will give you a wealth of information if you give him a call. He may be the best person to ask.
I fished the 3/4 snowbee switch line on my 10' 6wt, meaning something in the 6/7 size would probably be best for your 9wt. If you're planning on primarily fishing tips like all salmon/steelheaders do with the switch style casting, its better to lean on the lighter side of the grain window (ie 6wt-7wt switch line for a 9wt). HOWEVER, You cannot expect to be able to throw the heavy lead core tips on a single hand rod with ease like what is common place for steelhead/salmon fishing. T-11 -> T-20 will be pretty well impossible. Poly tips/versitips will be your friends in your scenario. I have casted the rio switch line, and unsure if i really enjoy it.
There wont be one line that will do it all. In order to do this properly its going to involve purchases a 2-3 different lines, and practicing, or taking lessons.
Few people on here have much experience with successful spey casting/fishing (myself included), we dont live in a province with proper fisheries to dictate doing so, we have the eager beavers who insist its this "new thing" thats really cool to do, however in few places is it practical. So i wouldn't be making your decision based on our advice from here. Your question may be better suited to speypages.com, or call fish tales in Calgary and pose your question, and buy your line from them.