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I doubt that Google cares. You need to be more concerned with what the webmasters who link to your product-specific site will think. The point of the 301 is to preserve incoming links, bookmarks, and PR. If the people who linked to your site and bookmarked your site find the new site irrelevant, you'll lose them.
If you have a page on your general site that is more relevant than the index page, 301 to that page.
You've stated that you don't want to continue with the product-specific site. If that's the case, you have a choice between a 301-Moved Permanently redirect, a 404-Not Found (by taking the site offline), or a 410-Gone (by keeping it on-line, but telling the SE's the pages are gone). Given those alternatives, you might as well try the 301, as long as it's relevant.
HTH,
Jim
The "abuse" is limited by several factors: First, the listing in the SERPs will be updated using the the new page as the basis - all you get to keep from the old page is the PR and the incoming link text. Second, there's the loss of incoming links/bookmarks I cited if the new page is irrelevant. And third, there's the "Spam Report" if your competitors spot anything worth reporting.
While there may be some automatic filters in place, and more coming in the future, I believe the "competitor report" is the most effective one right now. If you don't see a problem in that regard, then go for it.
Jim