Have you considered setting deadlines on key tasks? Deadlines are always as of the default end time of a day. So, in your scenario above the task would still be meeting the deadline (although there is finish variance). Tasks are flagged in the indicator column if you are scheduled to miss a deadline.

If you wish to test variance for every task, the formula below should work:

In a Flag field:

DateValue([Baseline Finish])-DateValue([Finish])>=1

will show "yes" for any task that does not have the same date value finish as the date value baseline finish.