I don't have the exact setup that you do, but I have noticed some interference when I have multiple sensors/computers on my bike. There must be a way to get it to work though because I've seen pictures of Hunter Allen's bikes where he has 3-4 powermeters on his in addition to other sensors. Not sure how he does it though...I've also seen some of the pro's riding with multiple widgets on their bikes too...

wish I knew the answer. hopefully someone on BF will have some insight into this