A flat plane (180 degree crank) V8 will have more vibration than a 360 degree crank V8, however, it will still be smoother than inline 4s, such as in S2000. IF honda goes V8 with next NSX, the proper way is to use flat crank. tiny engine vibrations in sports cars are acceptable. The sound and slight perfomance advantages should drive this. If Honda use the lazy 360 crank, off firing V8, forget it, I'll take a V6 instead.
Honda lack of developing a production V8 is getting ridiculous. Toyota, Nissan, and even Mitubishi has a V8. Mitsubishi has in the home market. I even heard Hyundai has a V8 under development. We all know Honda likes to do more with less, but that philosphy doesn't jive well in the luxury or exotic car market. If they keep this up, pretty soon, everyone's going to think Honda doesn't make V8 because they don't know how. Give us a small block V8 with 3.5 liter. The small displacement will satisfy the tree huggers and the high tune flatcrank V8 well fullfill the performance enthuiasts.