I'm not sure anyone has said short time at least in this thread and there are quite a few models of aluminium folding bike that have had frame recalls; Tern, Origin, SGM and a british brand I forget the name of. You also see reports in forums of folding bike frames failing occasionally. When Brompton and bike friday had recalls it was aluminium parts that failed and not the steel frames themselves. Bottom bracket for Brompton and handlebar stem for bike friday tikit models. There certainly has been reports of Dahon frames failing but not to the same degree as Tern of course.

I think it is fair to make that comparison, many people are riding very old steel folding bikes like Bromptons and many lightweight aluminium folding bikes do often have a relatively shorter lifespan before the frame fails. Not only that but in the rare instance of a steel frame failure it often can be repaired successfully and relatively cheaply. I'm totally biased though and have a preference for steel even though I don't have a Brompton. I honestly believe your average aluminium folding bike frame is more likely to have the frame break/crack but if Thor is right about the improved weight limits of this particular model it may not be the case here.

No suspension on the Curl though and the rear suspension of the Brompton not only makes the bike more comfortable for the rider and help isolate the rider from potholes etc for the very same reason it also isolates the frame from such jarring impacts because the load itself (rider) is not rigidly connected which helps reduce stress to the frame and reduce metal fatigue. I've read the Curl is an uncomfortable bike which you really feel the impact of potholes with and if you are feeling them you can be sure the frame is too.