uhh,...what? I know a guy who has been beating the crap out of 16 Cerwin-Vega T-36 earthquakes for about 18 yrs. now.
Congrats to that guy but statistically those results are irrelevent. Go look for used CV subs online and invariably most you find will have blown or non original drivers. These things should not be that fragile but they are marketed to DJs who as a customer segment are well known for abusing equipment, but CV has to take some blame for advertising them as a 30hz box which is a full 20hz below tuning.
In MY experience you start having reliability issues when there are chinese parts involved.
My experience with CV extends back over 30yrs when chinese components weren't a factor and even then you would be hard pressed to find a CV fullrange cab with intact high frequency drivers.