This is a tough one. I will try and provide as much input as i may so you can evaluate if either it is a good option for your project or not.
For starters, i am assuming that the only reason you may want a dispatcher set between authors and the Author instance they access to is performance; you may think that by using a dispatcher you will be caching "some" content so authors will experience much faster responses... But i think that is where the problem locates: what content can be cached for authors? are author's requests dynamic?
As you will come to realize, if not already have, when dealing with this type of questions it is best to run some tests, so i did. I installed Apache httpd and CQ5.4 author instance. When you are authoring a page you now that dialogs are actually forms (html <form ...> tags) that send post requests to server so that content is not cacheable.
The drawbacks i found and also the ones i can think of are:
1. how much of the cached content will be served? 20%, 30%?
2. extra system administrator elements
3. content is cached before being deliver to authors
The pros:
1. across different time zones this could be the only option to increase performance.
In my local test that i ran i found that getting content from dispatcher was 3 to 4 times slower than getting it directly from CQ5.4 Author Instances.
Here are other links you may find usefull
http://dev.day.com/content/kb/home/cq5/CQ5SystemAdministration/HowToConfigureDispatcherForAuthoringEnvironment.html
http://dev.day.com/content/kb/home/cq5/CQ5Troubleshooting/CQ52XLinkCheckerWrongExternalLinks.html
