I think you both have valid points. In essence, the use of gradient factors have highlighted two risks. First we know it is risky to dive close to the M Line. GF-hi mitigates this risk. We also now know (after the NEDU study and others) that having a wide GF spread, which creates deep stops, is also risky.
GF-hi is easy for divers to understand and set. But GF-lo is difficult because we don’t really know how much is too much. Maybe the diving industry and diving community have to rethink gradient factors. Perhaps the dive computer settings should have the GF-lo setting limited to a maximum spread.
I recut the data to rank the Presets by GF-hi and then by Spread. I highlighted GF Spread of 50-100 as being too wide. Unlike my previous sort, this one creates one big red block of questionable gradient pairs. Again, it is probably this block of pairs which should be left out of Presets and reserved for custom settings.
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