Just changed my HF10 for the above camera - and certainly not regretting it.
However, I'm just wondering what exactly the camera is doing in the manual exposure mode.
Say that I've chosen Av and set the exposure to f2.8.
If I've asigned the manual knob to exposure and increase or decrease it, what is it doing? The screen info says that it's set at f2.8. so am I in fact changing the shutter speed to compensate?
Likewise, in Tv mode with the shutter set at 1/50th, if I manually alter exposure via the knob, am I then opening or closing the iris?

I noticed the same lack of info and believe that it is indeed either adjusting the shutter speed or aperture depending on the mode your in.

You might try half-pressing the photo button (assuming the HFS100 still has one). That should display the current aperture and shutter speed. If neither are changing, then it might be adjusting the gain to achieve different exposure levels. It might also vary for different lighting conditions.

While I'm impressed with the Vixia line as a whole, I'm not impressed with the lack of display options. My Canon still camera has three separately customizable displays to choose from. With my HF10, it's all or nothing, and "all" doesn't even have everything I want, but lots I don't want.

You might try half-pressing the photo button

That's not working Kevin, although what is nice is that it's now possible to cycle through various display options - including a full 100% view so you can see what might be outside of the area normally shown on the LCD. Especially handy if using a microphone or lamps near to the subject etc.

I assume it to be increasing gain via the internal processing, but don't know that for a fact

What I'd like to know is if there's truly any way to lock aperture while in Cinema Mode, I've heard people claim something like this but can't find it to be possible on my camera