But still having severe problems getting the Impero to consistantly sync. Did some test setups and shots today, worked like a charm for 3 hours, swapped lenses, quit talking.
Here's the deal as I currently understand it based on my experience.
Wired mode works well. Wireless gets funky as batteries drain. I've also added longer antennas that seem to help the range a lot. Sometimes you lose sync by going out of range and by walking closer to the camera you get it back (newest firmware). I haven't tried the new antennas on a real shoot yet, but around the house they appear far superior to the little 1" one's that come with the units.
If you have trouble syncing with the mount try power cycling both the Impero and the Birger. Hold the I button on the Impero when you power back up (after a couple seconds you can let it go). Be very close to the camera when you're gaining sync. Sometime I stick the antennas right next to each other.
I know the Impero had (has?) a weird bluetooth bug where it won't sync when you first power up. The second power up often works. Seems like the Birger mount may do something similar because unplugging/plugging it seems to help.
Some lenses can cause the whole thing to shut down. My Sigma 50MM 1.4 is very erratic.
Once I get the first sync of the day things seem fairly smooth after that. Now I don't wait longer than 15 seconds for a sync before I try power cycling. That's saved me a lot of time and frustration. I also have a 10 Foot wired cable that is fine for many/most situations.