Genesis

There is a trade-off here.

If you restrict flow you solve the problem of a too-rapid add but increase the risk of a hypoxic event during a rapid ascent as the solenoid will not be able to keep up.

Also, there is a power consumption issue. Solenoid valves consume huge amounts of power compared to the rest of the electronics. Stepper motor driven valves do not except when moving, of course, but there are patent issues with that, as well as potential practical issues as well.

There are ways around all of this but as with all design choices you have to be aware of the compromises you are making, why you're making them, and the side effects.

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