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.
Thanks, Max — I did test it, and it works fine in a controlled situation for all of the event types tested. My main concern is whether this goes against best practices since I’m essentially taking a vendor spec and creating a customized variant that melds all of the event types together as one long list of optional segments. On the other hand, I suppose if it gets too unwieldy during the build process it wouldn’t take much to split them out.