Last October, I bought a Sage ZXL 9 foot 4 weight. It was time to replace my old reliable Sage SP 490-3 that I sold to gent who said that he had to have that rod. (I needed the money.) I use this rod primarily for fishing dry flies and soft hackle wet flies.
The rod is definitely an improvement over the SP. It still has that medium-fast action, but it's slightly quicker. It also feels lighter. It fishes well within 30 feet. It fishes well at 60 feet. What I like best about it is that it loads smoothly. For slinging dries and soft hackles, I prefer to slow things down a tad since presentation is everything. It seems to just fit that need.
I originally used a Scientific Anglers Trout Taper WF4F that I won in a raffle. It worked well for that rod except for situations that I needed to stretch out a roll cast. I changed to the Rio Gold WF4F line from the suggestion of the Sage sales rep who I met at last winter's Fly Fishing Show.
AbelBoy
PS I actually nymph fished with a big puffy indicator and two flies and two BB splitshots. It actually did ok (but not great). Then again, I would normally use my 5 weight for that situation.
If your looking to be doing roll casts, the Rio Gold is probably at the bottom of my list...The Gold has a thin diameter running line for distance and is pretty much a standard dry fly, overhead casting line. Plus its 1/4 line size heavier and you don't need that for the ZXL...
If you do a lot of roll casts and want superior line control while mending, get a double taper. A SA Trout DT-4-F will rock on that rod. It has a welded loop, dry tip technology for superior floatation, AST for shootability, and comes in a dark willow color for stealthy presentations. Rio makes a good line in a DT called Selective Trout II, but there isn't a loop and it doesn't shoot as well as the SA Trout. The Selective trout a has a long front taper for a really delicate presentation for small dries (think Tricos and baetis), and the SA Trout will give you more options when you decode to toss that size 12 humpy and micro may dropper.