I have been using Scientific Anglers 8WF Bass Magnum on my 7/8 . I originally had a 7Wf but the 8wf really picks up big streamers and poppers easier. Roll casting is pretty much cake. Just a flick and a the line flips a popper or clouser off to a new spot. Really just sucks it right off the water.
Have the 4, 5, and 5/6 weight also. Technically the 7ft. 5wt is my girlfriends and I'm jelly cause it's a great rod.
The 6'6" 4wt casts great with an old dirty re-used DT4, love it.
The 5/6 I haven't had long and I'm not so sure I like it with the 6WF I have been using. I think maybe I'm just so used to using my 7/8 which has the same length as the 5/6 that I'm expecting a similar feel, but it's not there. It's like I want it to be another bass rod, my "bass lite", but it's really my "trout plus".
These rods are roll casters, they all seem to roll cast better than most rods I've used. That's why I like them. Put a tad heavy line on, get used to the way they feel (slow, heavy, sloppy) and once you get the rhythm down they just start working, almost casting themselves.
P.S. Is it wrong that I've used my 7/8WT for trout and caught more fish. Feels like cheating. Absolutely crushed one day in high water on streamers when trying to cast with any lighter rod would have been futile.