The 5CP models that end in W have a "one time" lifetime replacement warranty. The "special brass" models are supposed to resist washout much better but have no replacement warranty.
The 5CP2140.3000 is the same as the standard 5CP2140 but with high-temperature seals. AFAIK there is no 5CP series with stainless inserts. They all have stainless steel valve assemblies, but no other stainless parts.