different class c's but all the same nameserver

Try it yourself and see, there's no point asking here, you'll get a bunch of useless replies from wannabies and 2bit tgpers, and anyone who knows will give you an incorrect answer as you're his/her competition.

my thoughts exactly.

They do take nameservers into account, but if you have different class C's, it shouldn't affect you much at all.

could be but i also believe there are at least some helpful peeps around..

sounds good

I wouldnt worry too much about different Class Cs unless youve got one hell of a huge network of sites - in our testing here having seperated class Cs made no difference whatsoever to SEs responses and listings and having studied networked sites for over 5 years and specifically effects in Google since the notion of separation was first put out 4 years ago, until sites started flying high above their radars, nothing ever happened. What I mean by flying high, is doing other stupid things like posting that they are selling links for PR on message boards, running cloaks on the same sites they were networking or other things that brought Googles attention to them.
The answer about nameservers - again if attention is brought to your sites for something else, nameservers are easy for Google now as they are a full registrar with script access to the whois database.