GCPBA board member Blakely LaCroix and Peter Werness, Ph.D. did a formal scientific analysis of the performance of coolers in different configurations.  Their released results are available here:

Article 1:  An Evaluation of Drained vs. Un-Drained Coolers.
Cooler Research Article 1 Drain vs No Drain

Article 2:  An Evaluation of Block ice vs. Cube ice.
Cooler Research article #2 - Block ice vs Cube ice