Firmware upgrades are more likely the answer. Verbatim may work better for some but no all of us have the same drives...so it won't be the same for everyone. I've burned 2 AVCHD discs on Sony Dual-Layered discs and had NO problem burning or playing.
I actually have some Taiyo Yuden discs and those are for my special videos.....like Adywan's stuff.
Anyways.....not everyone's experiences will be the same.