Recruiting reviewers is a hard job, almost too hard. This could pose a problem. Since PI's spend so much time preparing their proposals that they've spent that time the prior. Shaming them into volunteering makes no sense, and they are busy, their time should be spent doing what they do best. Using the un-implied strategy of reciprocity to get previously funded PI's to volunteer to review is suspect. If there are not enough solid reviewers in that exact area of science and the latest and greatest innovations, then the review process relies solely on "nice use of white space" - I am sorry, but I don't have the confidence levels of the PR from the NIH, so I give their review process a 5.
