Basically what you have described above.
As it stands, we don't recommend the internal adapter.
But the fact is this is all experimental.
In the long term, we want OSMC's Bluetooth streaming to work well with it. And if there are any issues we are confident we can get it to work and contact Raspberry Pi developers and give them a stack to work with to improve things.
But for now things are experimental. This test thread is alpha testing and with Kodi Krypton it will become beta testing. We are committed to improving this however. Especially as AirPlay, which was previously used for audio streaming is likely disappear in a future version of Kodi.