BillyS - 1:57 pm on Aug 23, 2010 (gmt 0)
You really think a site would drop in SERPs because it changed external links to no follow?
I do think there is a pretty good risk anytime you make a site wide change like this. Especially since it's not how Google intended the option to work.
Too many webmasters are worried about PR juice and try to hoard it. If a link helps your visitors, then leave it. If you're selling text links, then a nofollow might be appropriate.