goodroi - 8:45 pm on Nov 6, 2012 (gmt 0)
#1 If the content isn't good enough quality to help the existing site why bother moving it to a new site?
#2 Personally I love niche sites but it is getting much harder to generate the trust factors that Google is moving towards with smaller sites. It really depends on each specific situation.
#3 Why aren't you thinking of redirecting the old site to the new site(s)?