I just tried the hifiman leather pads on it, and yes I agree, it tends to improve the sound a tad bit. However, I find the Alpha pads more comfortable due to more supple leather and deeper cups.
I've never liked the Focus pads. The velour on it seems to give me the itch.
The treble on these phones should be used as an example by all manufacturers. Some magic that I can't explain.
I used them as a reference point for others to compare to.
I would say this headphone is only beaten in soundstage and nothing else, (by HD800 & HEK).