Audeze and Hifiman possess entirely different house sounds though (and rightfully so), and most people tend to just choose one or the other depending on whichever house sound they dig more. That is typically a very rapid realization, unlike your process, where you do not gravitate toward one house sound or the other.
LCD2 (r1 or r2) has never been and will never sound fully "open", simply due to its damping scheme. That arguably is a big plus to the HFM orthos, for those who care.
Yeah they do possess a different style. Although this difference seems much larger when you're coming from one or the other and have been using it for a long time. Once you experience and live with both, the differences become smaller and smaller. They are to me more similar than different. I'll say that getting used to and appreciating both is a cost and more so, a time investment.
What criteria are you using for "openness?"...Personally felt the LCD-2 and LCD-3 as more natural and 3-D enveloping, making it more enjoyable and giving me more freedom, even though HE-500 is more wider, has more air, higher treble extension. I never felt as if there was an awkward wall on either of the Audeze's, especially not with LCD-3. With HE-500 though, I couldn't move forward or jump up and down.