And it's these kind of posts which just reinforce my feeling that the attitudes against the Wiimote for FPS are based on a faulty understanding of exactly how to use the controller. I will admit, Nintendo did shoot themselves in the foot with their advertisements depicting people holding their arm up perfectly straight and pointed at the screen. It looks awesome in an ad, but no one would find the Wiimote comfortable if they had to do that. However, that's simply not how anyone who's really sat down and played with these for extended periods would use it.
Best way to understand it is to think of staring down your arm and the Wiimote to aim as equivalent of you zooming while using a sniper rifle. You don't go walking around doing that every single instant of playing an FPS game, I'm sure. Most of the time, you're really going to be shooting from the hip, as it were, relying on your targeting reticule to aim. We do the exact same thing with the Wiimote. Most of the time, you would keep your hand either on an arm rest or in your lap (exactly the same posture you use for a traditional controller is perfectly fine, and perhaps even optimal), moving more with your wrist than anything else. You certainly shouldn't be getting any shoulder strain, because your shoulder shouldn't even be in use there. Nor would you need to stand up. When you relax and play like this, the pointer effectively becomes the same as a mouse cursor, and it doesn't take long to get used to the range of movements you'll need to make to move that cursor around.