The PC3K8 has pretty light keys for a weighted action. The V-Piano is also on the lighter side, but not as light as the Kurz.
Velocity curves do not affect how heavy the action is, it only changes how hard you have to hit to get a certain level out of it (the actual feel of the keys doesn't change at all).
A board with a high quality heavy feel action would be Kawai VPC1 which has no sounds (it is just a controller). If you want something with built in sounds, look at the Kawai MP-10 or MP-11. Other boards with a somewhat heavy feel (but lighter than those Kawais) would be any Yamaha with a GH action (CP33, P155, P255, etc.), or a Korg with an RH3 action (i.e. SP250, SV1). The lowest cost board to look at is probably a Casio PX-150, which has a nice feeling action and is also slightly on the heavy side.