There is an assumption, correctly or incorrectly, Google punishes or at least does not rank well sites with sitewide links. What are your experiences? Do people fear that in the future they could come unstuck in the face of a Google algorithm change even though they may be ranking well now due to too many sitewides. For those that do not rank well, possibly as a result of too many sitewides, are your sitewide links compensating for lack of good rankings?
As I understand it sitewide links are generally counted as just one link to Google. Google probably won't punish a site for having sitewide links because in some ways that's the nature of certain kinds of linking, such as blogrolls. Also, if you run more than one site it's pretty normal for them to link to each other even if they are sitewide links. I would just try to get a good mix of links of different kinds. Sitewide links won't kill your site, but there are enough easy ways of getting non-sitewide links that you should have no trouble getting enough non-sitewides that it shouldn't be an issue.