Ich habe die selben Erfahrungen wie Du machen dürfen mit einem großen Forum. Ich würde nie wieder umziehen mit etwas was viele Seiten hat. Selbst die Umleitung in den Webmaster Tools macht den Umzug nicht besser.
Es ist auch interessant was Matt Cutts zu einem 301 sagt:
https://www.abakus-internet-marketing.d ... 80976.html
Eric Enge: Let’s talk a little bit about the impact on PageRank, crawling and indexing of some of the basic tools out there. Let’s start with our favorite 301 Redirects.
Matt Cutts: Typically, the 301 Redirect would pass PageRank. It can be a very useful tool to migrate between pages on a site, or even migrate between sites. Lots of people use it, and it seems to work relatively well, as its effects go into place pretty quickly. I used it myself when I tried going from mattcutts.com to dullest.com, and that transition went perfectly well. My own testing has shown that it's been pretty successful. In fact, if you do site:dullest.com right now, I don't get any pages. All the pages have migrated from dullest.com over to mattcutts.com. At least for me, the 301 does work the way that I would expect it to. All the pages of interest make it over to the new site if you are doing a page by page migration, so it can be a powerful tool in your arsenal.
Eric Enge: Let’s say you move from one domain to another and you write yourself a nice little statement that basically instructs the search engine and, any user agent on how to remap from one domain to the other. In a scenario like this, is there some loss in PageRank that can take place simply because the user who originally implemented a link to the site didn't link to it on the new domain?
Matt Cutts: That's a good question, and I am not 100 percent sure about the answer. I can certainly see how there could be some loss of PageRank. I am not 100 percent sure whether the crawling and indexing team has implemented that sort of natural PageRank decay, so I will have to go and check on that specific case. (Note: in a follow on email, Matt confirmed that this is in fact the case.
There is some loss of PR through a 301).