Panasonic 12-35 stabilisation with GH4 is out of this world. I did a music video and an interview with it handheld, unbelievable.
Yeah, I've seem amazing performances on video with the stab in m4/3 that could justify in itself the all system.
Originaly Olympus was famous for having the best stabilization of digital age but Panasonic caught-up and with the dual IS all the comments I read and the footage I've seen is quite impressive indeed.
Just a certain caution with panning as it could fool the brain logicaly but with a bit of practice it is la crème de la crème.
The fact that the sensor is small helps a lot the engineers to build a state of the art IS compared to other systems.
As Canon rules AF, m4/3 rules IS.
The thing is that the BM has no ibis, so it looses a big benefit of the mount, but has a long list of enourmous advantages for the filmaker (and it will have Prores Raw in firmware).
The design, specs and price are spot-on.
The BM is more a specialist camera than the GH5, offers more on what it's designed for but the GH5/G9 do good stills too. There are professional photographers who embrassed the m4/3 movement over FF, unthinkable a few years ago. The system has matured a lot.
I'd buy this BM anyway because it's small, cheap, perfectly designed and really powerfull. It will fit like a glove in any prod model and I think they will sell a lot (waiting list)
Now for Vlogging as I heard, it's overkill and pointless.