A hopefully simple feature to implement that would help my workflow considerably would be some keyboard shortcuts. I'd like them to cover the most often used stuff while attempting and tweaking capture:

Play
Pause
One frame forward
One frame backward
Move
Rotate
IK
Camera 1
Camera 2
Camera 3
Camera 4

How about the following candidates:
Play/Pause - Space
One frame forward/backward - Right/left arrow
Move - Alt+M
Rotate - Alt+R
IK - Alt+I
Camera # - Alt+digit
?

Any keyboard shortcuts would be appreciated :)

If possible I'd avoid the alt-modifier, as if you need an awkward hand shape or need to take your hand off the mouse, the utility of the shortcut is rather diminished for this application (as the mouse is used so much for tweaking the model).

My suggestions:
Space for start/stop is ideal
, and . for frame back/forward would avoid having to move the hand significantly
1 2 3 4 for the camera views would be good, with no ALT modifer needed
M R I for Move, Rotate, IK - again with no alt modifier.
Alternately, Q W E, thus grouping the keys up with the camera view controls.

This is just me being UI and workflow focussed, the suggested keyboard shortcuts would also be gratefully accepted :)

Ian, thank you for your valuable feedback!
After thoughts and discussions we implemented this feature exactly as you described because your variant is optimal in terms of usability.

Check the latest version of iPiStudio - 1.0.0.107

Woohooo! Thanks guys that's fantastic :D I'm happy to have helped a bit :)