Ageed, it's not a given that you will get hinge problems with a Dahon. But it is also true that Dahon has rather an unhappy hinge history. Supporters of Dahon maintain that it is a very small percentage that develop hinge problems; this may be true but I hold the view that especially the handlepost hinge is such a safety critical part that any failure at all is reason enough to contemplate a recall. Dahon did not do this for a long time while hinges continued to fail sporadically. They did in the end issue a recall, but not before a complaint was lodged with the relevant authority in the US. The hinge design was since modified. But I think they neglected/ignored the issue too long and I have lost confidence, permanently. It was very significant indeed that the first big thing that came out with the new Tern, was a very sturdy, serviceable hinge - a huge jump forwards from the original Dahon hinge.
And reports about Dahon hinges giving trouble still pop up with some regularity. At the very least they require some babying to keep them in tiptop condition, something not so necessary with other brands' hinges.
Ah, I thought you were talking about the frame hinge, which is why I responded so. Yes, you are correct that there was a handle post recall that led to a redesigned hinge. What the nature of that redesign was I do not know (Thor does have a tech bulletin up on his site from awhile back, and there were some diagrams, but I didn't look closely), but it's hard for me to believe it was a wholly and willfully poor design issue, and was probably more a user issue. You obviously feel differently, and have decided Dahon don't know what they're doing. Clearly, I don't feel that is a fair conclusion to draw, but it's one you have the right to hold, and may even be right about.
However, whatever you may consider an "unhappy history" with hinges at Dahon-- and I am one who considers that, as the most prolific and successful producer of folding bikes in the world, Dahon issues are sure to take on overblown proportions on the internet-- new bike purchases will have the revised handle post hinge, and so will not be, to paraphrase you slightly, a "primary source of regret for getting a Dahon."
It's my opinion that using that kind of language, i.e. regretting Dahon purchases, is inaccurate, misleading, and indefensible given the hundreds of thousands, if not millions, of satisfied users. I don't know the exact numbers of Dahons sold and resold, but the only way for a bike company to survive 30 years and become the #1 brand in the world of folding bikes is to generally make quality gear. That kind of high profile also makes them easy targets, both for volume and their visibility. I'd guess that in a given day, Dahon sell more bikes than Brompton and Bike Friday sell in a month combined. That makes for a much bigger rumor and misinformation mill, which is something that we as humans have proven to be quite predisposed towards.
Every company makes flubs, from Apple, to Ferrari, to Dahon. At which point a consumer throws in the towel and loses confidence is a personal decision, and not usually a rational one.