I dunno, dude. I skated lots of Girl boards and I loved them. I don't know if it's mental or what, but riding those flat boards made my ollies so proper and I learned a lot of tricks on those things. That's just about all you can ask for. I rode super concave-y Deluxe boards for a long time, and the switch to a flatter board made a change in my skating for the better. They do have a weird cheapness to them, like how the graphics sorta flake off instead of rub off. But I guess all heat transfers are like that, right?
I personally hate flat boards. Nothing to grab onto, nothing to work with. In my head, it makes more sense that boards with more concave are better for flip tricks because there's more to flick off of. It most likely doesn't make the least bit of difference and it just all depends on the psychology and style of skater, I guess. My friend's Flip completely blows for shape, for me. It's flatter than a piece of 2x4.
I ride Zero or Toy Machine or Mystery. Soon to be Mystery, anyway. I've never tried one, but I do know they're under the same distribution as Zero, obviously, so I hope they don't feel like the Shallow Grave shape, because I don't care for it. Afterlife is the better shape of Zeros, to me. I have a Cole Angel of Death 8.12 right now. It features the Afterlife shape and I love it, it's so curvy, like a boat hull, but the width is kinda beat now. I got the stability I needed from it, now I'm gonna go back to 8.