Hello all. I am new to this site and new to Jeanneau. But I think I do have some insight. I also have a 43DS and unfortunately have not been able to sell my Cascade 44 yet do to other challenges.
Here is what I have to offer. On my Cascade I added a 130% Roller Furling Headsail and a behind the mast Roller Furling Main sail all for the benefit of my 110lb wife (I was too lazy to crawl out of bed to help change sail plan). The Cascade was alway overpowered with a huge main sail (20ft boom) above 18kts wind, very much weather helm. But when I put the Main Furler on, if I too about 2 feet off by fuling the main, I found I could get up to 25kts wind without fighting the helm and didn't loose any real speed.
While in San Diego last week sailing in and out of the bay to ocean, my 43DS was acting much like my old cascade. So I though I would give some shortening a try. I first rolled in the Genoa which did two things, releived the helm and also gave me a better view under the Genoa. Wind was about 18-20kts. Still had a little weather helm but I was clocking 8.5kts over water. Thought that was neat so I took in about a foot on the main and the weather helm was completely gone and was still clocking 8.5kts over water.
I orginally thought I wanted to do the same as you but after some playing with the shorter sails I have given up the idea completely for all the reasons previously mentioned.
Now I am spending my money on a removable bowsprit by Selden and adding a A2 Gennaker by North Sails and may opt for a storm. Got enough sail for heavier winds but not much for the lighter ones downwind.
Hope this helped.