Letting a pod of any kind ripen allows it to fully develop its sugars, so the flavor of ripe will always differ from the flavor of unripe. You should know that some people prefer certain varieties green and others ripe, but only you can judge your individual taste preferences. Even if 1,000 people say they like the flavor of something that does not mean you will. Many people like the flavor of orange habaneros, for example. To me (and to others I know), I like the initial hit of their flavor, but then I get a strong ammonia-like taste that is entirely unpleasant. More habs for others to enjoy is my perspective.
Heat? Yes, allowing a pod to ripen also increases its heat, but c'mon - - it's a poblano; don't expect much.
Crosses of poblanos with a chinense? Probably, as annuums and chinenses cross fairly easily. Any marketed as such? Not that I know of.