Well here you go, first impressions about Heaven VII. First of all, here's what they have in common with the Lab1. Similar shape and feel, though Heavens are heavier of course. They share the Lab1's effortless sensibility, so very musical, but with lots of detail contained within. With both headphones I feel like I can hear the room reflections of the locations that recordings were made in, and can tell what's room sound and what's added reverb, etc.
The Lab1s are quite a bit darker than Fi-Ba-SS, with much more low end, though never dull. The Heaven VIIs fall someplace in the middle. They have more high end, less bass, but still more bass than the Fi-Ba-SS. In a sense, they are what I wish Fi-Ba-SS had always been, that magical musicality but minus the slightly harsh treble, and with more bass. The bass is not heavy, but there is enough to be satisfying, improved when you have a good seal.
I find the Fi really only good for classical and jazz, but they really excel there. The Lab1s are enjoyable with acoustic music, but really shine with rock and heavier sounds, as the darkness makes loud music easier to listen to. The Heaven VII give the upper frequency detail of the Fi but with the relaxed easy-going vibe of the Lab1. Some might call it excessive, but I'm so glad to have all of them.
After trying to find multi-BA custom IEMs that really pleased me for years, and many pairs, I have been pleasantly shocked to find the most superior sound in these little universals.