basspig, I ran a search on the bitrate meter, and it appears that it's not as helpful as other machines, because it only tells you the combined bitrate of both audio and video, and not separately.
While there might be a few that hope for a FW fix, others wonder if the hardware can support it, and believe it's not such a simple thing. Furthermore, some consumers believe if the split meters ever come, it will be a while because it is considered low on the list of priorities.
I hope you find what you need!