Honestly, if you want a coat that seals up well in bad weather, then a duffle coat is not the best choice. Toggles and a hood without drawstring are not ideal.
If this was in a response to my post, then I've previously had a Monty duffle in use here in Finland. It was one of my favourite coats. Admittedly there were days when I wished it had a belt to tie up around the waist to stop the wind blowing up. The front and toggles were less of a problem. So my question was specifically about the effective differences between the 3-toggle and 4-toggle version, and their functionality.
They were used by the Royal Navy in what I'd assume were pretty harsh conditions. Though who knows, maybe they were more of a chilling out coat