Heh... I don't know where they came up with the idea that SELECT INTO is slow... especially if the target DB has no triggers or keys and especially when the target is a Temp table that lives in TempDB with the SIMPLE recovery mode set...
SELECT INTO enjoys the same mimimally logged and non-logged benefits in TempDB (again, SIMPLE recovery mode) as does Bulk Insert and BCP provided the following are true (from Books Online) ...
The recovery model is simple or bulk-logged.
The target table is not being replicated.
The target table does not have any triggers.
The target table has either 0 rows or no indexes.
The TABLOCK hint is specified.
I will agree that a very large SELECT INTO will keep a lock on one of the system tables and will keep similar ops from running until it is complete. But, even for a million rows, if the query is quick, there won't be much interference (should be scant seconds).