I have. I do films as opposed to events.
My plan was to use the gh2 for insert shots, closeups, places where dof makes sense
with the 150 in a wider frame
I did it as a multicam shoot. In low light, with mostly candles as light.
GH2 lens was the pan 20mm at 1.7f,50fps shutter, 24p 1080,
150 was 24p 1080p with shutter at 48 and f at 1.7
Key things I noticed:
1) make sure you black balance and white balance both cameras- the gh2 made the candlelight yellow, gh2 more white.
didn't see this until on a big monitor. even if the lighting changed minimally, there immediately was a considerable difference,
2) gh2 way brighter in low light
3) gh2 image quality well beyond 150: 150 gets noisy in low light. gh2 much less so. The difference here is less apparent in brighter enviroment
where the 150 improves.
Once I learned I needed to to white and black balance everytime anything affected the lighting or when I repositioned the camera, the color
match between them was better.
I would use the gh2 for shots where quality of the image really matters, and the 150 for master shots.
In low light, it might be worth just using the gh2 with a fast lens.
I have the GH1 and splice it with the HMC all the time, the GH2 should be the same way. You will get a sharper image and stronger DOF with the GH, so i usually use it for close ups and eye candy shots. You dont want to cut similar shots together as you can immediately tell the difference. And like Chauncy says - if you have fast glass you can pull more light than the HMC150, but thats typical with any DSLR/fast glass combo. Regardless the HMC150 is a very solid camera in low light... You always should consider adding light rather then pushing gain no matter what camera.
Yes as said the GH2 tends to be yellowish but clean, while the HMC is noisy. The GH1 is ok in color but one has to get a way aroud the verticle lines. Im getting myself into events, and i can say that i've even tried to get the DVX100A match, and what i see is that the GH1, HMC150 and DVX100A can be forced to accept each other, while the GH2 doesn't like the family get together.