I am not sure about that. I did some surveys bout a year plus ago and most systems I found did not had the flaw. But this is pointless. For this info to be valid we would have to have a current study and even then I am not sure if it can be presented as evidence because it is just heresay. I think (but not sure) that one would have to present either the author or a pro that would testify to the accuracy of the report.
Survey shmurvey. I've tested myself at least 4 routers that I can confirm are vulnerable. They could be compromised in little as 10 minutes but some took a few hours. Dlink: dir-615 dir-628 dir-825 Linksys: WRT54G2 And my router is also vulnerable. But I've mitigated the problem by having a renewal of the key/reboot at intervals that are typically shorter than it takes to crack the pin.