Alternative Rewrite Rules result in a significantly simpler .htaccess, especially one that doesn't constantly need to be updated by WordPress. This is particularly practical if you also use the .htaccess for other purposes. Additionally, Apache is not necessarily faster with the complex Rewrite-Rules from WordPress. I have activated them myself, let's see how WordPress 1.5 performs with these entries. If there are no problems, they will stay that way, because I like them much better than the other variant. And they don't have the problems that the others have - old mod_rewrite can only do greedy matching, which makes creating complex lists of rewrites quite hairy ...