I've found contrast enhancements such as "I.Contrast" on the Panasonic TM700, and "DRS" on the HMC40 very handy for certain situations. However, "I.Dynamic" on the GH2 does not seem to function. It produces no change in image or histogram. Is this feature working for others?

I don't know. I have it on, on my EX3 version of it to bring out detail in high contrast video. Not sure how you would check it on the GH2. I am just hoping it works. I see an example on the Pany web site but it looks rather subtle .