At the risk of annoying those who do have a preference for a specific
type of first stage design, the simple answer for most divers is NO
the design type of the first stage does not matter. Piston type
first stages are simpler designs with a lower parts count and thus
generally considered to be more reliable. Environmentally sealed diaphragm type regulators are generally considered better suited to diving in near freezing temperatures. Keep in mind that much of the opinion often heard expressed is a
result of theoretical considerations or manufacturer marketing, not
based on the actual characteristics of modern scuba regulators. Today,
both piston and diaphragm first stages are very reliable and high performance balanced versions of both designs can flow more gas than the diver can breathe.
