Well, unfortunately we are in the same boat. I never thought about optional parameters and thus haven't tried it before. It's an interesting idea though. Rather than not populate them, I would assign dummy values to the unused ones. Then if you need to, in your report logic check for the dummy values and act accordingly.

I don't think that answers your question. Binding to a custom class is really talking about using that class as your data source. Thus, your report prints the data from that class instead of from a database. The parameter collection isn't involved here at all.