I tend to agree with Mark that it's ok to have two Success statuses. If you are using RCA/RCM, you may seem some different MT attributions, but I'm fairly sure successes are counted properly for the Program regardless of which Status has the success.
On an individual Program level, you'll end up having two separate Statuses though.
So if you are running a lot of the second type of Program, you might just want to break those out as a separate Channel Tag and then you can properly report on this type of event vs. actual Trade Shows.
What I usually do is somewhat similar to Marketo's defaults:
Trade Show
-
Registration List
-
Met at Booth
-
Requested Call
Roadshow (either our owned event or smaller event)
-
Registered
-
Attended
-
Missed