Hi Edward,
I'm a high school teacher in CA (and former elementary school teacher). Yes, WBT can be very demanding when it comes to your energy level. However, if you have a low energy level, students get bored and lose focus. I think it is important to remember that you can adapt WBT to your personality. Using WBT does not have to be as high energy as many of the videos show. For me, I focus more on thinking about gestures than thinking about maintaining my energy level. You asked if there are teachers who shouldn't even try WBT. I think I see more resistance to WBT in the high school community than in the lower grades. It has been my experience, that teachers who are looking for ways to engage their students really like many (not always all) of the aspects of WBT. I think it is definitely worth exposing as many teachers to WBT as possible, and then they can decide what works or doesn't work for them. Many teachers, who might initially be resistant, might be surprised how much they get out of WBT training!

Good luck as you continue to teach teachers. I think it is great to give teachers new ideas to help improve student learning!