Stored procedure

I would agree to first look at the fn!executestoredprocedure() node over the smart service.  However there is a trade off in performance - if you are utilizing a number of calls at once, such as to validate each row of a grid, you will note better performance with the smart service.  This is due to the function not having the same Run Validation parameter that is available in the service, which you can set to false so that the call does not re-validate the procedure data types, etc, on each evaluation.  The function will automatically re-validate the procedure during each call and you will start to notice performance degradation if you call it multiple times at once.

Saying that, I also prefer the function for one-at-a-time calls to a stored procedure. 

One additional note to include, we have had a few situations where we could not use the smart service (MNI limitation), and needed to perform a number of stored procedure calls with the function, at one time, validating multiple rows of a grid.  Performance was not great, so we actually setup a web service that would call the stored procedure instead - from the interface, we call the web service, bypassing this plugin, and performance is actually phenomenal.   We get something like 1000 calls in 1 second (depends how well your procedure executes of course).