A few things:

- while .NET does make it relatively easy to go either way, it's not the only language. Most of the other solutions tend to have issues dealing with stored procedures returning more than one recordset, so if you need a recordset out of your stored proc AND something else, output parameters are going to become a convenient way to do that.

- If you want something new from a stored proc, you're going to need to change your code no matter what. I'm not sure that any one method is better than any other?

- Output parameters make it easy to pass info between stored procedures.