The Center for Lobbying in the Public Interest has issued this important report.  From the executive summary:

Many of President Barack Obama‘s ethics and transparency efforts have been justifiably praised. But his decisions to restrict who can serve in the executive branch and on federal advisory commissions based on whether they are registered under the Lobbying Disclosure Act (LDA) have been repeatedly criticized. After two and a half years of experience, it is clear that these public service restrictions have done little to curb special interest influence in Washington, while unintentionally harming public-interest advocacy and undermining the Administration‘s efforts to promote transparency and good government.
This report focuses on an often overlooked aspect of the Administration‘s restrictions — their impact on nonprofit advocacy that is required by law to promote public purposes rather than private gain. Information has been assembled from an online survey and interviews of public-interest advocates, data on LDA terminations and the public record. While by no means a scientific study, this report represents the most systematic effort to date to canvass nonprofit leaders and determine the real-world consequences on their organizations and the public interest.
The findings are disturbing.

While shrugged off by some within the Administration as unimportant collateral damage, this report finds that the problems with these restrictions are quite serious.