what we have seen is that the redirect of userdisp.aspx into the ssp profile page only works from a given site collection when the site collection's 'portal site connection' is configured, AND the 'portal site' (web application) specified contains a 'my site host' provider. in addition, the redirect only works for the matching AAM zone (ie, if the portal site connection url matches that web application's default zone, only the originating site's default zone will redirect). this is a bug! none of these requirements makes sense!
userdisp.aspx _always_ redirects to the ssp profile page on the web application hosting the 'my site' provider, with or without a portal site connection specified, and regardless of AAM zone. so something is different about the behavior of a web application containing a 'my site' provider. in our view, ALL site collections should always do this redirect, regardless of AAM zone, since each web applicaiton should be getting the 'my site' host information from its associated SSP!
can we expect MS to address this issue?