recently bought a 6.5G carboy, and didn't like what I was hearing about the krausen blowing the bubblers off,('specially since it's in the dining room....I was warned that if it made a mess, to the cold **s garage I was headed)so I went the same route. Left the larger one capped, but attached the 7/16 like you did.
Took a day or two to build up steam, but I got big bubbles something like every 2 seconds in my bucket. You can see, the krausen reached the neck, but nothing came through.
The only thing I notice was that when I took off the cap to thief a bit for testing, it seemed like it didn't seal right, right away. I could smell the gasses coming out by the neck, so I'd play with it a bit, and finally it seemed to settle in and start burpin' away again.
Overall, I like it, just need to look at the engineering of the seal to see if I can improve on it.
