It doesn't matter to me how Opeth puts out an album - just that they do. They are my #1 band by far (yes, this is a Nevermore forum, and Nevermore is my #3 favorite band behind The Tea Party), and I just wait for the release of this next endeavor.
I personally, though, can't imagine and ENTIRE album of clean vocals without any growling, or visa versa. Even with songs like The Funeral Portrait and Demon of the Fall, the vocal switch in the endings is magnificent. I wonder what the songs would be without them - probably just as good, but just wondering.