[ejones]

Code sharing really only becomes a compelling argument if you're building browser games or something similarly interactive (i.e., really bloody interactive). In this case, you need to run the same logic on the client (to reduce latency) and on the server (to validate and actually update game state).

Otherwise, you really have no excuse for putting logic on the client. Even with something like validation, I think its much more sensible to have your renderers pump out generic validation event handlers than to reconstruct the whole model class on the client.