Each has some advantages. In retrospect, the main disadvantage of the Curve is the frame design, which allows only a very limited range of chain lines; but I'd guess Dahon has fixed that, if they're offering it with a derailleur gear now.
OP is comparing the Curve SL model vs the Mini. The SL dropout is wider so the chain line is not limited.
I owned these two bikes and did not have a positive impression from the Mini since the frame had a protrusion were the seat tube slides and it scratched all the seat tube. Yang recommended me to file the protrusion, which was "standard" for ~5% of his bikes to get them and that he was going to send a new seat tube, but it never happened. Also the sturmey archer hub was not as nice as the nexus hub, due to the constant adjustments and drag. There was also a dust cap below the suspension that kept falling until I lost it on a ride. Apart from all these I also noticed that the hinges are the same ones that cheap folding bikes uses (eg like the kent folding bike I owned). Don't get me wrong, but these hinges seemed to do their job well. However, I am not sure how long they will last. The kenda tires were not that good since it slipped on curbs with steel on the sides. Least, but not last you will need something to keep the bike together while folded since it does not have a magnet and the seatpost is not as long as the dahons. What I liked about the bike was the suspensions, price, and that it accepted 100mm front hubs and standard sized seatpost. I ended up selling the bike. I don't doubt if you end using 200+ to upgrade the mini you will get a comparable or better bike than the Curve SL.
Regarding the SL, the gearing was a bit low and replacing the chainring to a bigger one was not an option since this will make the chain rub with the frame. Also it is 2x the price of a mini. The rest you should know since you own one, I mean your wife
. Hope this helps.