The most loyal of MR readers will find this old hat, but the debate at this link, originally done for Reason magazine, provides a good summary of my views. Here is my bottom line:
To the benefit caps that we really agree on, Glassman wants to add government-regulated personal accounts. The economics here are straightforward, once unbundled from benefit caps. Our government would raise taxes (or borrow) to finance further private investment in equity markets. Furthermore those investments are to be regulated by the government. I expect that Reason readers, once they hear the plan described in these terms, will be suspicious.