Saying 'irreplaceable' is conjecture, isn't it? Yes without Steve Howe can still be Yes but a different kind of Yes. I do like Trevor Rabin but Steve Howe's barbs at him from the Union tour are always funny. 'He's playing where there should be no playing!'
Triumph without Rik Emmett is another example. Phil X is no Rik Emmett so Triumph's last studio album didn't really sound like Triumph asi