Both my fusion & lucid are flat; i mean they come up to the shoulder then flat. While the biofuzion has a moderate dome; but it's still comfortable to grip. I don't have a giant, world or enforcer next to me (they're downstairs) but the rim of the defender feels extremely similar to the giant & enforcer. the world differently feels wider, obvious difference. I've only had 4 rounds with the fusion & 1 round with the biofuzion, that being said, the fuzion flys just like the tp giant but with a little more glide; just as stable. And that's why i love it and kicked the giants out of my bag. Biofuzion is just as stable, but it's also 5g heavier. Now the lucid i haven't gotten the chance to throw it yet.
Excellent for flicks as well, they come off very clean. I hope this was helpful.