It's not a "lingering feeling". It's a fact. The Zeiss Ikon is absolutley not a Leica. Other than the M-mount, it's a completely different camera than the M4, which is a heavier, all-mechanical, meterless camera. The ZI, on the other hand is a nice lighter weight camera with AE & a modern meter. Each has its place & it's nice tohave the choice.
His comment seems to be fairly typical of someone who has been using a certain camera for 30 years. The replacement just never quite feels right. However, that is a statement more about the person than about the camera. I have no idea what he means by a "more together camera" nor do I know what difference it makes. As I said above, they are 2 different cameras. To each his own. 🙂