A very good paddler can control any boat with any paddle. In general, it sounds as if you just need more experience and practice, and perhaps some instruction. The Adirondack Canoe Symposium would be a good start, particularly if you can find an instructor who will concentrate on bent paddle usage.
Some more specific comments:
I paddle flat water and sit and switch. I can't figure a decent/comfortable j or goon stroke that doesn't feel like it's putting on the brakes.
This is confusing. If you are paddling sit & switch, you don't need to do any correction strokes at all. You just do forward strokes and get your paddle out of the water at, or slightly behind, your hip. Don't drag the paddle way behind you. Sit & switch also involves high stroke rate paddling even for cruisers. Depending on your hull shape and switching skill, you can do four to six strokes on each side before switching. Yes, this means you will yaw your way across the lake somewhat.
That said, some boats are simply designed better for sit & switch paddling -- in particular, the best hulls are very hard tracking. I don't know anything about the Keewaydin 15 other than it's heritage and what I can see in the video below. It seems to me to be a new version of a Yost kneeling canoe -- meaning it won't be an ideal tracking canoe for sit & switch paddling. (But, again, a really good paddler can do it.)
In addition, the Bending Branches Black Pearl does not appear to be an ideal switching bent. It has too big a blade and is too heavy at 14 oz. There are other videos on the paddle in which the BB owner describes the Black Pearl as a touring blade. To me, this all means the Black Pearl is better as a correction stroke blade than a switching blade.
It feels like I'm doing twice the work to turn and maneuver my Keewaydin 15 and I'm having to make exaggerated sweeps to get similar results of a straight shaft blade. That seems counter productive to the benefits of a bent paddle.
A bent shaft should be significantly shorter than a straight shaft, and hence it will not have the same leverage and reach on a sweep stroke as the longer straight. To make turns easier the Kee can easily be heeled, as the video shows. You can also use slight heels to induce on-side carves to counter-balance an uncorrected forward stroke with a canoe like the Kee. Charlie Wilson calls this the inside circle forward stroke, and he teaches a class on this technique at the Adirondack symposium.
Finally, to paddle straight with a single-sided correction stroke (i.e., no switching) using a bent, the third video below gives a good demonstration of the J-stroke. Personally, I would use a shorter bent paddle than Dave Woolridge in the video, though he is in a fairly wide boat.
I've also never cared much at all for the traditional stern push-away J. It's tiresome on the wrists and forearms. I like to start the forward stroke with a slight bow draw and use a Canadian stroke recovery. In the Canadian (or forward lifting loaded slice) recovery, you don't push outward with the paddle way behind you. Just behind your hip, you slice the paddle forward while lifting slightly upward. This pressure straightens the boat and also moves the paddle part way to the bow for the next stroke.
You can find videos of Bill Mason and Rolf Kraiker doing the Canadian recovery with a straight paddle. Surely there is one, somewhere, of a good paddler using the Canadian correction with a bent.