Just to clarify for those who aren't aware, Carl is on this new recording by way of old vocal sessions for the song. Therefore talks about not achieving the pre-1965 blend because Carl is absent are wrong, although of course Dennis is not on it.
The disparity between the 1965 and 2008 voices of Brian should be noted too though as a big obstacle.
True, though I've always been quite surprised at how well Brian fits back in with his more worn voice. Such as the 1985 performance of Their Hearts Were Full of Spring: http://uk.youtube.com/watch?v=7Vy4eVYJQrs