Haven't heard Heartland, but Rognir P does compare very favorably to D8000 Pro. Actually they are surprisingly similar, both of which offer a very engaging and dynamic sound which may not be perfectly flat on a graph, but do sound highly satisfying. Both are on the warmer side, with elevation in the bass; D8KP has more bass than RP with stock pads, but RP with non-perforated pads (ECL-03MF) has noticeably more bass, with significant elevation in both sub- and mid- bass frequencies. I would say that D8KP does offer overall better bass quality, with slightly more resolution capability than RP; the difference is small, but noticeable. Mids and treble are definitely more similar than different; extension is excellent, but more reference-inclined listeners would probably want more elevation in the mid frequncies, where both headphones have some tonal quirks which prevent them from being perfectly flat. I found this to be a net benefit, however; both headphones are more forgiving towards imperfect recordings than something like Utopia, which does measure more flat but can get a bit harsh at times.
Maybe the biggest thing going for Rognir, is its closed-back design; with any non-perforated pads installed, the isolation is significantly better than any open or semi-open back design; whereas with D8KP you need a completely silent room to enjoy it to the fullest extent, with RP you can have a less-than-ideal listening environment and still get a true TOTL experience.
