Having worked with Merge Replication the 2005/2008 versions, I'd recommend not using Merge Replication unless it is the only option. It's such a resource hog and has too many pieces that don't work well for a dynamic database and schema like Kentico has. The limitations
Sandro mentioned would be enough where I wouldn't recommend any of my clients use Merge Replication unless they planned to modify a publication everytime a custom table or document type were added or modified OR it was the only solution they had or were offered by their server team.
I'm not stating it won't work, I'm stating it will be a maintenance nightmare for IT. This might not be the best option but it's not the only option.