I fish a 9'0" Sage Z-Axis as my "go to" rod for mid-sized streams and rivers; I don't stillwater fish much at all. It's very good rod, with what I'd call a fast action. It works well with dries, streamers, foam terrestrials, nymphs (both weighted and unweighted) and furry Prairie Dog-sized flies. It has a pretty good feel to it; particularly at long distances and has tons of reserve backbone for when you hook into larger fish. I've fished it for 3 years now and I've been happy with the way that the blank works for me. I'm sure that you know the rod well, but here it is again:
As an aside, I like the Z-Axis a lot better in a 5 wt. than I do the Sage TCX. I cast that rod in 5, 6 and 7 wts. and the heavier the blank, the more I like it. It's what I would call an ultra-fast rod and in a 7 wt. I liked it enough to purchase one and it's now my standard Smallmouth bass rod.
I haven't cast the Scott S4, but understand that it's billed by the manufacturer as a fast action rod. I do have a good amount of experience with their new A3 blank. I cast it this Summer in a 7, 8, 9 and 10 wt. and I like the 9'0" 9 wt. enough to make it my regular rod for fishing Stripers in and around the Kennebec River in Maine. It's a medium action rod with a wonderful feel for heavy payloads and when fishing with a lot of wind.
But, my wife fishes a Winston BIIx 8'6" 5 wt. and, to be totally transparent on the topic of your question, the minute she puts her rod down, I pick it up!
There's just something about that rod; the lightness in the hand, the feel, the presentations, etc. I don't know what Winston put into their BIIx technology, but they have a very, very nice blank there in my opinion.
I don't think that you would be disappointed with the performance of a BIIx in a 5 wt. Good luck!
---------- Post added at 07:04 AM ---------- Previous post was at 07:00 AM ----------
I would add that the action on the Winston BIIx is, for me, medium-fast.
So the action sequence on the rods above would be:
TCX - ultra-fast
Z-Axis - fast
BIIx - medium fast (tending more toward fast)
A3 - medium fast (tending more toward medium)