I have a trailer next to the Red Deer just West of Sundre and have been fly fishing it bit off and on for a couple of years. Was just getting to know it when the flood hit in 2006 and the river completely changed course and created a whole new challenge.
Watch the edges when wading as the gravel bottom has not settled and the sides break away quite easily, particularily where the edge drops into fast/deep water. That can be exciting if your wearing waders!
I learned to run backwards on moving gravel a couple of times, kind of interfers with the cast technique!
Last year was spotty but did manage to get a few browns and bulls in the 10 to 16 inch range and a couple of small rainbows, like 6 inches or so. Have not caught a cutthroat in there as yet, but that is not to say they are not in there.
Ran into a couple of kayakers last year when scouting the river above the dam, asked what the though of the float from Sundre to the dam, their opinion was it could be dangerous with many sweeps and underwater hazards because the upper end changes so much. These guys were well equipped and seem to know what they were doing. They also said unless you have a lot of experience floating quick water they would not recommend it.
I took their advice mainly because I don't have the experience, and I would probably not get in much fishing if you had to pay that much attention to navigation. My pontoon is certified for class 4 whitewater, but I would rather fish than swim!
Anyway, that's all I know so far, more time this summer will give me a better feel.
Was up there today, most of the snow is gone, river is low and a bit muddy. Hope it clears at least for May long weekend and then the run off can start, I'll head for the lakes til it clears.
Good luck.