Following on from my previous post about Project Server and PerformancePoint in a multi-tenanted environment, realised that I had not told the whole story!
I neglected to include this when I wrote the above, Excel Services is another critical part of Project Server (more so than PerformancePoint really), and although it does have some support for Multi-tenancy it is far from perfect.
In short, when you configure Excel Services (no partitioning options are available) it does appear to honour subscriptions in the configuration, ie you can use a tenanted Secure Store to create Excel Services Application IDs, however the catch is that it will only talk to the Secure Store in the Default proxy group!
This presents a problem, as you read above PerformancePoint also only talks to the Default Secure Store, however unlike Excel Services PerformancePoint can not talk to a tenanted Secure Store app in the default group so you are left with a catch 22. Either both Excel Services and PerformancePoint can work together using a NON-tenanted default secure store, or one or the other cannot be installed!
If this stuff were simple we wouldn’t be here would we?