@kensuf still trying to understand this and not trying to be an ass because there is likely something I'm missing.
Are the guys on the Fathom using the needle with a blocked first stage or with a normal one?
If blocked, why are they OK with adjusting the needle based on workload but are not ok with adjusting it based on depth and workload? The same risks exist with either scenario in terms of accidental adjustment, over adjustment, and failure.
They dive it blocked. It comes stock with a fancy spring and a fixed IP Apeks first stage.
My understanding is the adjustment is once or twice a dive max as opposed to continuous with a non-IP blocked first stage.
Think: scooter and deco -- one adjustment because you're basically at rest the whole time. If your flow rate was set to at rest on the last dive, then you really don't need to adjust it.
Think: swim and deco -- two adjustments, one for swimming (working) and once for deco.
When showing me the first prototype unit two years ago, Charlie warned me that it's possible to dork up a needle valve by over-tightening it -- something I'd think would be a risk if you're continually fiddling with it.
I've never dove a Fathom but I did dive with the designer last week and I slept in a Holiday Inn Express this month.