I took an older D440 from BVI to NY last year and brought a brand new one from Annapolis
to BVI a couple of months later.
Both sailed very well and fast (they used to regularly win the Cape Town
to Rio race
I seem to recall) and I was never concerned about their sea-keeping abilities. We had 47 kt winds and quite large seas on the way down and with 2 reefs
she was in great shape. All South African cats
have lower bridge decks than French or US built boats but I didnt really notice any more slamming than any other cat I've done those trips in.
The first, older Dean was in very good shape - I was quite impressed how well she had stood up to the ravages of time. The New one was not so impressive: I thought they had cut corners on final trim finish and there were quite a few problems, which however could be ascribed to any new boat on its maiden voyage.
Get a proper survey! Fair winds, Tony