Keep in mind big coolers with double fans are a lot of weight to hang onto a motherboard. Yes it has a backplate and all that, but it's still a lot of weight. With proper unobstructed airflow through the case, with plenty intake/exhaust, moving over the components, slight differences between coolers won't make huge temp impacts. My front case fans regularly work harder than my cpu fan ever does.
That's not to say that NH-D15 isn't a terrific cooler but I personally wouldn't use it for weight and clearance issues, unless I had a case/configuration where my mobo was horizontal and supported by the case. Even my NH-U14S is overkill but I like it for the bigger and quieter fan.
If you already have 212 Evo, I'd look into better case airflow, over a slightly better cooler.