To the OP, I have Murph's risers (1 3/8" I believe), and I ride the **** out of my bike when I ride in the local area. I usually ride with guys on sport bikes, and I've yet to see anyone show up on a heavier bike than mine lol. I probably ride the Connie harder than one should on a regular basis, but it's damn hard to ride it slow if you ask me. I don't find that the risers impact my ability to ride aggressively at all. I can't shift my weight like I can on the Ninja I just bought, but I can do what I need to do in order to control the big bike. The Concours is meant to be more comfortable than a sport bike, so there's already a lot of compromise in the riding position. Risers won't change things too much. I'll take the added comfort of risers over any minimal gain in performance I would get from stock grip height.
As for the extra hand pressure you experience during aggressive riding and braking hard into corners, like some others have suggested, try using your core to suppport more of your weight. You don't want to put all of your upper body weight on your hands as that will fatigue you very quickly. It takes some practice, but you can figure out in a few rides. You should be holding the grips with just enough pressure to control the bike. Avoid resting on your hands while riding. My father experienced some of the same soreness when he transitioned from a Gold Wing to the C14, but after putting more miles on the bike, he's figured out how to take a lot of the pressure off his hands. Another thing you can do is lower the windshield. This will allow more air to hit your chest and kind of hold you up, if that makes sense. When you go into corners, try applying pressure to the hand that's inside of the corner you're taking...right turn, pressure on right grip...left turn, pressure on left grip. This allow the outside hand and forearm to relax a bit. Obviously, you don't want to let go of the opposite grip, but you shouldn't be grabbing the outside grip with the same amount of pressure as the inside grip. I've put that method to the test, and helps reduce arm-pump significantly.