Okay, so The FXD80, MH1C, and FXD70 (source: Sony S545, volume on 30 for all three - wasn't that loud to my ears with these three, song was the Black Crowes acoustic version of Non-Fiction).
D80 = best black space between instruments out of all three. Percussion instruments (shakers) can be heard with great detail and clarity. Sound is very transparent and 3-D like. Plucking of guitar strings highly detailed with nice sub-bass, yet a balanced sound. Closer to stage than the MH1C.
MH1C = richer, heavier refined bass. Less black space and instrument separation than the D80. Percussion instruments audible but more buried behind major instruments (bass, piano and acoustic guitars). Sound signature is darker and rich, but doesn't touch the either JVCs on clarity and transparency of sound. Vocal have great realistic weight, but the D80 vocals are probably more forward. Instrumentation blends in (blur) together more than the JVCs.
D70 = Clearly the most neutral sounding IEM of the three. Nice bass punch but clearly least bassy out of the three. Just a cleaner sharper sound (like the difference between looking through a newly Windex cleaned window and a window with mist on it when comparing the MH1C to the D70. Less 3-D out of the three. Notes blend together nicely with superior clarity.
(Second song was Wings' Band on the Run listened to through last year's iPod nano 16gb at the highest volume)
D80 = Sharper imaging and clarity in notes than the MH1C, but the MH1C has heavier notes and more details in vocals and string instrumentation. Again, use of black space is outstanding.
MH1C = Heavier notes of the three and darker sounding. Really nice details but not as easy to breakout separation of individual instruments. Vocals are very nice in detail, but I don't the vocal are as forward as the D80. I think you're sitting farther from the stage, however with the Sony.
D70 = The same as with the other song. Great clarity, transparency and a more neutral sound.
Conclusion: It's really hard to say which is better than the other. It really depends on sound signature preference. So with that stated, I prefer the D80. The black space is really something special to me along with clarity and . I hate to use the word "veiled" but the MH1C is a bit compared to the JVCs. Next to the EX1000, the D80 and D70 might be the clearest dynamic IEMs I've heard. Both have great transparency and clarity. But the MH1C has a better stay imaging from front to back than the JVCs. The sounds of the JVCs are clearly different from the sound of the MH1C. There's no clear winner here with any of the IEMs outrunning the other. One does something better than the other and vice versa,, but all three are good (and the MH1C is great for the price). But again, my favorite is the D80 out of the three.