I do think that Battle Squadron (and indeed Hybris) was ahead of its time compared to other Amiga shooters, Xenon 2 and Sidewinder for instance - it's a much smoother, arcade-like experience than those two IMO, with a lot more going on on-screen -smooth-scrolling, loads of sprites, massive smart bombs (and of course 2 simultaneous players).
It took quite a few years for other developers to match it, BS came out in 1989 (correct me if I'm wrong Torben, was it 88 or 89?), SWIV arrived 2 years later, but I think that has aged badly compared to BS, especially in the visual/colour palette department. Then off the top off my head I don't think there was anything as impressive until Banshee, which was a much higher-spec A1200 game, 5 years later.
Apidya is great though, although horizontal rather than vertical - I interviewed the guys behind it (Kaiko) back in issue 67 of Retro Gamer, their's was a similar story to Torben/Martin's, just trying to push the machine and see what they could get out of it, striving for an arcade-like shooter experience...