I would not take a single suggestion from the Database Tuning Advisor as safe. I would assume that each and every suggestion is suspect until I tested it. I do not trust it, at all, to get things right. And I know that sometimes it gets things wrong.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning