Just this week I decided to stop forwarding some of my domains and made landing pages. I made a basic splash page with the same header of one of my sites. I added the header to a few hundred domains. With redirects I was getting sign ups each day now more bandwith and much less conversions with referrals. Figure everything is considered duplicate content if you share headers and footers. Easy to copy and paste but your going to be hard pressed trying to rank any whitelabel site let alone an exact navigation bar on every site. I just didn't think the result would be as bad as it is. I will advise do not do this. What i am not about to do is change it back I think with enough unique content on each site I will over come the navigation bar duplicate content issue.