Spike, I like Winston rods, and if I were in your shoes and had the money, I'd go and buy a Boron IIx 8 weight for the applications you mention. I own one and it's my favorite saltwater rod.

But since you already own the Sage RPLXi 7wt., why not use this rod for those steelhead and smallmouth? It's a great rod with lots of reserve power. RPLXi rods received an extra layer of graphite in the butt section in order to provide that power down low. Not only do these rods work well for fighting fish, but they can also handle heavy sinking lines and large flies -- heavier and larger, in fact, that what an "ordinary" 7 weight might be able to handle.

Although it's a personal preference, I much prefer the hardware on the RPLXi over the newer Xi2. I feel like Sage took a step backwards with this new hardware.

That RPLXi may be discontinued, but it's a very capable and smooth rod. Best of luck!