Bob Schmelzle was pretty fond of his T&T 12 foot 8wt single/double the year before I moved east. In fact he landed two steelhead the morning I fished it with him.
Bill, I would recommend a 9' 6" 8wt instead of a 7wt personally because the typical summer conditions (August / September) have depleted oxygen levels in the water for potentially very large fish. An 8wt does a much better job of bringing the fish to hand expediently. In reality I have not fished the 7wt 10 footer but I have fished the 8wt extensively and it's a great casting, mending, and fishing tool.
As you know my preference is for a two-hander in most cases simply because of the amount of coverage you get on most streams. Even when using a single hander, you'll end up Spey casting whenever there's brush behind you. The 7136-4 Sage is a great summer run tool, although in some cases it has been a little soft for fishing sinktips - to get the hook set well on long swings.
On bigger rivers like the Sky, Cow, Hoh, etc. - you'll probably use the big two-handers anyway. A 7wt is a pretty whimpy tool for these rivers in my opinion. I got totally smoked by a chrome Hoh summer run on my 15 foot 8/9 Loomis. I dunno how I would have fared with a 7wt single hander?
Then there was that guy, ironically named Bill, on the Cow with the 7wt 10 footer. Never saw anyone hit so many summer fish in such a short time! At one point he followed four fishermen thru the pool and still hit a 17 pound buck. Every fly he had in the flybox was a black woolly bugger. He fished a homebrew line with nearly a full sinking head section spliced to a running line. His target zone was very close to shore where most people stand, and he only fished in the evening and early morning (period).
I caught a nice 12 pound hen the day I met him. He was walking around killing time and came over to see the fish. He told me he never fishes until 5:30 or later and that he had caught seven that morning. I thought he was full of ####.
Later on I passed by his camp. We talked further about the fishing, and he showed me his box full of black woolly buggers while thought I was cool flashing the wheatley full of summer speys. Then he popped open his cooler... and there was the biggest, brightest, thick shouldered summer buck I'd seen all season. It was awesome to behold, even dead (hatchery).
He, his freind, Lou and I fished together that night. After Bill landed the first fish he moved the the back of the line, where he continued to land fish playing clean-up behind us. The last fish he landed as the lights went out was a buck just like the one he kept that morning.
From what I could see (even though I was too proud to study him) he fished the edge of the fast water and the soft water near shore, shaking his head at how far we stood in the river. He swung the fly hard, leading it with the rod aggressively. I think I detected a little twitch in the hang down imparted using his stripping hand, but I am not sure about that.
Anyway, don't know how much help this was for rod choice but it was fun reminiscing about a few great times on the river with some big steelhead in the pools.