I am making an assumption that you are referring to the Sage Z-Axis 5126-4. You will find yourself not having enough backbone to throw large wind resistant leeches or heavier stonefly nymph with a Skagit head and heavier tips during the winter Steelhead run. I'd err towards a 6 weight to give yourself the versatility.
Edit: Should also add that you will wish that you would have more rod if you hook up with a 12 to 15 pound American River Steelhead in the fast current (especially if it is still chrome).
Last edited by MoscaPescador; 12-25-2012 at 11:55 PM.
Reason: added something