After reading about Viper I could imagine that this would be a good way to store nsf data in DB2. Instead of using BLOBs in tables for the nsf data move the XML representation (DXL) under the hood of the XML engine in the upcoming Viper.
What would you gain comparing to the current DB2 integration in Lotus/Notes 7?
You could retrieve data trough a well known standard query language xquery instead of proprietary views.
This would open the proprietary nsf container more to standards and business needs.