There has been much debate here on forums in the past on this topic.
I am personally of the opinion that an external visualiser is much better than an internal one....this way there are dedicated resources for each task.....much like DPs process their own DMX signals.....a visualiser is just another node in the network.....I feel this type of architecture is much more powerful and flexible......but others disagree.
Our general opinion is the same as what Marty has stated. An external visualizer is the best option so a lighting console can focus on the tasks it needs to be doing.
Is there a plan to release on for the pc like the grand ma is doing. They have a free visuliser that will connecto to any of their consoles. The new release is going to look like wysiwyg and esp.
At this time we are not planning a visualizer similar to the GrandMA visualizer. We prefer to keep our developers working on consoles and developing new features for the consoles. However as resources and demands change, this too could change in the future.