I always go by the rule that you should try to avoid them at all cost. I am not sure your application which would help in answering this topic. If you are trying to do a moment resisting frame, that would be a bad idea. I have seen cantilevers work well.
The problem with moment connection is that wood changes shape over time. It shrinks or grows depending on moisture content. This would lead to slop in your connection and you will not get a true moment connection.
Craig