If in doubt, try it!! Setup a test xlate and send messages of different types through and see what happens.
Choosing the message type for new xlates or reconfiguring existing xlates simply determines what part of the variant is show in the xlate, but it does not determine how the message is parsed. For HL7, the message will be parsed based on the value in MSH.09.02. If your paths are different for different types, then you can reconfigure the xlate to see the paths for each different type. But, like Charlie said, its much easier to make every time look the same using optional and repeating components.
