I don't think these guys are saying that the reason they like the replacements better is because their voices are shot now. I think they are saying that even in their primes they couldn't sing as good as the replacements. And in 95% of the cases (especially Foreigner) that is not true. I like Kelly and he is a good replacement since Lou can't do it anymore but Lou in his prime was twice as good as Kelly even on his best day...

http://www.youtube.com/watch?v=MfHKyfrx2zA

Listen to the feeling that Lou puts into every line. Listen to the way he comes up from under the higher notes and hits them with such ease instead of coming down on top of them like Kelly does.