I finally got some good footage of the Spirit flying. And by "good" I mean the flying was good; the footage was only ok. I managed to override the auto focus on my phone, so it doesn't try to focus on nothing, but the footage is still a bit blurry.
The Spirit may be a little frustrating for a second plane. It has no dihedral so you have to constantly use ailerons to keep it flying level. The tail is still a bit undersized, so you get a lot of adverse yaw too.
It would be pretty easy to add some dihedral which would help make this a more hands-off plane.