Information can be exhausting to convey so I'm going to keep this short.
Brett, smart money would go to a trip with a knowledgable guide. It will cut the guessing game down a lot. I am not trying to sell you a trip, I'm trying to save you a lot of fishless trips. The best way to fish the Clinch is with a boat. It's big water and there's a lot of places for fish to go. The Clinch isn't the same as it was 3-4 years ago but it still has good fish in it. I'm hoping this is just a cycle it's going through. I've moved fish on the Clinch that would turn your hair white. The Clinch and South Holston are almost entirely different.
Yes, most, if not all, of the rainbows you caught on the South Holston were stockers. TWRA quit stocking browns so they were most likely wild. Don't let this get you down, though. I was up there fishing the first mile or so this past September and had a blast catching those stocker rainbows. I fished one run and caught maybe 40. For a while, I was sticking a fish on every drift. Like I was telling you before though, get to know the REAL South Holston. Spend some time exploring it. It's loaded with wild fish but catching them can be tricky. Also, don't be fooled by the sulfurs coming off throughout the year. The real hatch occurs in June and July, and it can be incredible. Winter is baetis, midge, scud, and blackfly time, though!