Took longer than anticipated, but just got the Beer Gun last week.
I'm all for DIYing an inexpensive solution, but I had some poor results with the BMBF on beers carbed to over 3 volumes.
I don't think you'll have success bottling beers over 3 volumes with ANY filling device at the homebrew level. The beer gun should actually do worse because it doesn't have any back pressure mechanism.
The only advantage the BG should have over the BMBF is the CO2 purge. The downside is no backpressure.