Is C-class difference is that important to pass PageRank? What if my sites has 200.122.1.1 and 200.122.1.2 IPs? Will PageRank be passed then?
I don't think C Class has anything to do with page rank?? are you worried your sites won't receive "link juice" from other pages because your sites are all on the same c class?
If you use big virtual hosting, you can notice that there are hundreds of sites sharing same IP. I do not think they have any issues receiving pagerank
Different C class IP has nothing to do with PR. If you do cross linking between your websites, each of them will get PR leaked anyway whether they are hosted under different class C IP or not. The meaning of different class C IP usage is for cross linking to manipulate websites ranking without penalty given. All websites are owned by same owner. That is a kind of trick and a Grey area. I would not recommend trying to game over Google this way. It is possible to be identified by domain ownership as Google is a registrar themselves.
The C-class IP addresses and hosting packs are in most cases liked by the webmasters working on link building for their clients. Since using some affordable hosts, the links generated would be coming from different IPs, so it could be estimated that the SE results would be better but the matter could be completely different from PR.