I'd like to start by saying that the ticketing/Cardwall integration was desiged with operational work management and service request management in mind. I agree with your positives. I've elloborated on your potential negatives below.
1) The Service Desk would have to work in two user interfaces (Tickets and Cards)
This depends, you can set up a process where a manager converts a list of tickets (Changes,Service Requests, etc...) to tasks within a cardwall. From there, technicians can take responsibility and manage the converted ticket without having to engage a ticketing queue elsewhere. For example, once upcoming changes have been approved, the manager for that area would convert the changes to tasks and the technicians would update the change once they executed the activity.
2) We would need to create an "Operations Project" to capture all the cards that were created from Incident or Service Request tickets not related to an actual project. This could skew our Project Portfolio Statistics (We do think there is a way to not have it show up in the stats, but need to check in to it further)
Your correct about having to create an "Operations Project" to capture the cards converted from tickets. Schools who do this will either use the project classification or project type field, both are configuarable, to designate if the project is operationally focused. Having the "Operations Project" appropriately marked will allow you to filter them out when pulling together certain portfolio level reports.
Additionally, the "Operations Project" will still allow you to capture needed resource allocation information for more robust resource reporting and capacity planning.
3) Potential challenges on reporting ticket status. It is our understanding that while you are working on a card, the information does not transfer back to the ticket until the card is completed/closed.
This is true. The ticket's status will remain "converted to task" until the task has been completed. You can however, set up task level reports to filter on just "converted tickets" then display their associated status (card wall list) for a better understanding of the ticket's status. This report can be consumed via dashboard, email, or on demand.
Does this help Bill?