The final word(for now) on Import/Export
The folks at SQLTeam have done some analysis on different ways of importing text files, you can read the info here;
https://weblogs.sqlteam.com/mladenp/articles/10631.aspx
https://weblogs.sqlteam.com/mladenp/archive/2006/07/22/10742.aspx
And of course Gert has a ton of good data on high perf loading here;