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I didn't go over all the values, but from the quick glance I took I got the impression that the numbers aren't different at all, the updated script just writes out more digits. If it is indeed the case that limiting the number of digits in the output replicates the data as it is then the only changes would be in the file headers, and those are small enough that we can easily handle them in #16976 and this pull request wouldn't be needed.

Does the unified IO interface allows to set the output precision somehow ?

See the example with the formats argument in our documentation.

If you can get the diff smaller with the precision thingy, that would be nice. My two cents, FWIW. Thanks, all!

Thanks ! I think I got the diff smaller by forcing outputs to 10 digits. I updated both PRs.

It looks to me like the original format is 12 digits in total (meaning 9-11 digits to the right of the decimal point depending on how many digits there are to the left of it), but without trailing zeros. If there is a way to force the new data to be like that then it should be possible to make the diff much smaller.

I don't know how to achieve what you're suggesting. I also suspect that it might also have to do with Python 2 VS 3.