I am looking at the same two cameras, the HMC 150 and GY100. I posted an inquiry today and hadn't noticed yours until after I posted. The missing drag & drop function for Final Cut is causing me the most hesitation.
Some of the reviews on the GY100 said that they had problems with adjusting the iris while recording, that it jumped between settings rather doing a smooth transition. Some complained of it's very small size, and others liked the size because it was well-suited to going unnoticed while shooting gorilla and less intimidating on interviews.
I look forward to getting some feedback on the comparisons between these two $3,500 prosumer camcorders.