You'll be able to hang, but it may be better if you went with the Rio Grand or SA GPX as it is a half size heavier and better suited to faster rods.
I have the ST 4wf and have been pretty happy with it on a medium 4 wt. I have been able to "lob heavy nymphs" as Dean said, though not very comfortably if it's all day. I like the SA XPS better though...
If it's a great deal, then go for it. But I'd maybe look around first.
line changes, change