Welcome to WebmasterWorld Guest from 188.8.131.52
Forum Moderators: phranque
Are you thinking about something specific?
From the usability standpoint, having your page cached generally means faster access (and simply an access, if you website is temporarily -or permanently-, down), for advanced users... and if a user find what he wants, on your website, he might come back.
The majority of users, however, might not even know what it is about (well, some might have already heard people talking about it, on forums/blogs), and will generally not follow the "Cached" links.
For pure search engine optimization (better indexing), I don't think it is taken into account by any search engine... they will still index your website as regularly, and I don't think they would make websites "lose points", because they requested the engine, not to archive them... (well, I never read anything about it, anyway, and it would not make much sense).
This said, disabling archiving, means your website will not be indexed by archive websites, like archive.org, which might be yet another point of entry, to your website (and would permit users to see "how your website looked before", in a few years... -which adds a bit of community feeling).
Now, it depends what kind of website you are publishing...
I can't see how it would be of benefit. Does it really matter if Google does not show a link to a cached copy of your site in the serps? If it had a positive impact on rankings I would imagine that every site out there would not allow the SE to cache their sites.
Take a look at what Google has to say about it: [google.com...]
Make sure your web server supports the If-Modified-Since HTTP header. This feature allows your web server to tell Google whether your content has changed since we last crawled your site. Supporting this feature saves you bandwidth and overhead.