No, that guid is not used by the /Blog/RSS.aspx page unless you have specified a feedburner url in settings of the blog.
If you specify a feedburner url and are using feedburner, then ultimately requests for the feed must be redirected to the feedburner feed url, but we don't want to redirect at the time the user subscribes because we want his feed reader to subscribe to the real url not the feedburner feed url, after he subscribes we do want to redirect requests from his feed reader to feedburner and this happens once the guid is expired/changed. So if feedburner is configured for the blog we check this guid and if it is the current one we don't redirect to feedburner.
If you don't have a feedburner url specified in the blog then that guid is ignored completely so it cannot affect anything or break anything.
If you are not using feedburner you can leave that param out of the url for whatever is consuming the feed.