Then, you have a much more insideous problem to watch for. If you do nothing to prevent it, LINQ to SQL has been known to pass all character based parameters as NVARCHAR. If you play those against a table that has VARCHAR columns, then the entire column will be implicitly converted to NVARCHAR which also makes it impossible to do an index SEEK.

It's also tough for auditing. It's also been known not to pass certain parameters if the value it's passing during an update is the same as the current value especially during the same session. That means you can get a NULL in your INSERTED "Modified By" columns in an audit trigger.