To your last line -- I've got a PHP sub-system that I would love to have re-written to match our chosen stack language set, maybe simply because we could then h

To your last line -- I've got a PHP sub-system that I would love to have re-written to match our chosen stack language set, maybe simply because we could then have fewer required skills on the team (few of us are PHP guys). But for all its warts, it works. And that matters. I am thus hesitant to re-write for no other reason than 'we hate it'. It would be a lot of work for zero functional gain. (All benefits would be non-functional - and that stuff gets put on the back burner)