Most of the migration projects I've been on take 6-9 months to move stuff over. With that in mind, I usually always suggest going to the latest release because we're then well past the first 6-8 weeks when everything breaks if it's going to. Also, it extends the support life of the product by at least two years.
"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