I've owned a lot of glocks. I have owned and shot glocks since their 1st gen frames, and currently shoot glocks competitively. I have seen one kaboom in person and it was not my gun. It was a G35 set up to shoot Limited Division in USPSA. The kaboom was not a glock problem, but a reload problem, a double charge of powder in a reload. It would have kaboomed any gun. I have seen one other kaboom from an on-line site, with pictures posted. This was also a double charge of powder in a competition gun. I have also seen in person case failures in a G34 at a competition. The brass was bad and failing with very low powder charges. Not kabooming, but blowing out at the webbing and venting gas into the mag.
Then again, I have seen both of these happen with STI competition guns too.
I have never seen any glock kaboom that was a result of the gun. It has always been the result of ammunition and would have been an issue in any gun.
The Glock 40 S&W chamber could be a little tighter and support the case webbing more IMO, but it is FAR from unsafe. Any other caliber in a Glock is just as safe. This is an issue of excessive ware on brass for reloaders (the unfortunate guppied brass), and NOT a kaboom issue in any caliber in a glock. The glock kaboom is a myth. Reloader kabooms (and the 1 in a million factory round double charge) are NOT a myth.