Okay, so the number of runs of a Perl program in which this feature comes into play approximates to:

Count *every* run, of *any* perl program, *anywhere*.

Divide by that number where $^M was set.

Divide by that number that a death handler was entered at some point.

Divide by that number that ran out of memory at that *at that point*.

Divide by that number that are running on an appropriate OS.

Divide by that number that constitute an application the might benefit.

If 10% had $^M set, and 10% of those enter a death handler at some point, and 10% of those coincidentally run out of memory, and 10% of those are running on an appropriate OS and 10% of those could benefit from their death handlers not running out of memory before dying,

I make that 0.001% of perl scripts that might benefit, which makes my million to 1 shot guess look prescient.

If, like me, you consider that 10% is at least an order of magnitude too high for at least 2 of those, and 2 orders of magnitude to high for a third, then you the figure is more like 0.0000001%, which makes the million to one shot look positively optimistic.

Anyone want to buy some alien abduction insurance? :)