I did compare IM50 to GR07be. GR07be has more bass and treble extention than IM50 but also has sibilance issue unlike IM50. IM50s mids are more forward and natural sounding (great for vocals). I prefer IM50 over GR07be. I wrote a review here:
Great review! Pretty much the same as my impression for IM70
I also prefer IM50 & IM70 over GR07BE
When I listening IM50 and IM70, they made me forget of all technicality that I use to bother when testing earphones / headphones, and just let me enjoy the music...
IMHO, IM50 and IM70 should be put on earphones Wall of Fame