What I said regarding boats needing a stronger and stiffer hull did not refer to Halberg-Rassy or Dufour 410, both non performance cruisers but regarding a comparison between a main market cruiser and a performance one like the Dufour 410 and the Dufour 40e or the Halberg-Rassy 412 and for instance an Arcona 410. The performance boats have bigger rigs, bigger RM for the weight and need to have a stronger hull to take the bigger generated loads.
Actually I am no fan of Halberg Rassy. Currently, in our waters (west Black Sea coast) there are a few Halberg Rassys (from 31 to 43) and I am not impressed by their sailing ability. their owners sail them as daysailors which lacks sense. You cannot have a fun sailing such a boat.
In my post where I was surprised that someone would downgrade from Halberg Rassy to Dufour, I meant that there are other fast both performance and non performance cruisers in the higher quality level, like the Xp/Xc which Dufour 410 or cannot match. And since price is to a big extent a measure of quality, I would say that if I have got used to Hallberg Rassy and want something faster, I will be looking for a new boat within similar price level (X Yachts, Solaris) and would not opt to buy a Dufour 410GL/40e, though I may charter one, (unless my buying ability has downgraded as well). It is like with cars, if you had a Volvo you would not switch to Peugeut, but may be to a BMW if you can afford it (and I take for granted that a current owner of relatively new Halberg Rassy has the means to switch it for a boat in the same price league).
P.S. On the official detailed PDF brochure of Dufour 410 GL they write that the hull is hand laid polyester fibreglass. maybe they can upgrade everything but that will add a lot of cost and may be the boat will not compete that much with other more expensive brands.