OperationCaller Varadic Templates

Hey,
I just ran into the limitation of operation arguments.
Orogen reports the limit is 4, but the code looks more
like 7, which one is correct ?.

Apart from this, if we would change the implementation
to use variadic templates, there would be no limit any more.
Downside is, we would force a C++11 compiler.
Opinions ?

Greetings
Janosch