I think Matt put it best- the Heller is like the big Airfix kit at half the size- very nicely done. I haven't built the Heller kit, but I've seen built and unbuilt examples of them in person and they're very nicely done. I do have the 1:12 MPC version of the Airfix kit- unfortunately it is VERY incomplete, so I'm building only the engine as a display piece.