Trial/Free & Full Version VS. Free App + In-app billing?

Question

I'm just wondering what would be the best strategy to publish an application on the Android Market.

If you have a free and paid version you have two codes to update (I know it will be 99% the same but still) and besides all the popular paid apps are quite easy to find for "free" in "alternative" markets. Also if you have any stored data in the trial/free version you lose it when you buy the full version..

On the other hand if you put a free application but inside you allow the user to unlock options (remove ads/more settings/etc...) you only have to worry about one code. I don't know the drawbacks of that strategy and how easy/hard is to hack that to get all the options for "free".