Following to that Schema.org - Why You're Behind if You're Not Using It... article on SEOMoz, I must say this question is not just about microdata and Google SERPs positions. I think it has to be taken in a much wider meaning:
Some advantages:
- Implementing microdata on a website DOES increase CHANCE for Rich
Snippets displayed next to your site on Google search results. You can't say 'microdata = rich snippets', but you also can't say 'no microdata = no rich snippets' :)
- Having rich snippets increases users' attention to that single search result and it CAN result in more clicks => visitors on your page.
Some cons:
- Some rich snippets, which can be a result of using microdata, can let users find information they're looking for directly on the search results, without actually reaching your page. eg. if user is looking for a phone number and see it on rich snippet, he doesn't have to click and visit your page.
You have to decide on your own if you can take that risk. From my own experience (and that article comments as well), that risk is quite small and if you can, you should implement microdata. Of course, 'if you can' should really mean: 'if you can and it won't need the whole site to be rebuilt' :) If you have more serious things to do on your site, you should put them in front of a queue. Today, it's only 'nice-to-have', not 'must-have'.
And just for the end - I know my answer is not just yes or not the answer, but it's because the question is not that kind of question. However, I hope it could help you make your own decision.