The two referees have provided detailed, constructive appraisals of the manuscript. Some of the comments relate to requests for clarifications and additional information, which can be addressed relatively easily. However, other comments will require careful and convincing responses. Referee #2, in particular, indicates that thorough and thoughtful revision is required to address the concerns raised in that review.
The author responses address all review comments in detail, and new calculations were performed to confirm/extend the statistical analysis. This material will certain strengthen the manuscript.
The authors are requested to revise manuscript accordingly, to reflect these responses. To facilitate re-review, it is also critical that the authors clearly mark all revisions in the manuscript. The manuscript may be returned to Referee #2.

The authors have done an excellent job of addressing the referee comments, and further strengthened the analysis by including new statistical evaluation (which resulted in the same conclusion). I am therefore please to accept the revised manuscript for publication.