Personally, I think the OBDIIC&C is an indispensable tool for the Insight. For example, being able to monitor state of charge in real numbers, not just vague illuminated bars, helps you get the most out of the battery... It's really a tool for monitoring what your car is doing, with an emphasis on the IMA system, which other 'scan tools' don't do. On top of that you can read the standard OBDII codes - it does that automatically every time you turn the car on with the gauge plugged in...
So... I'd recommend the OBDIIC&C unless you've got about 0 dollars or you pay about zero attention to your driving, and what you're driving...