the IE8 upgrade sounds nothing like an IE8 in the end due to the 8.5mm dynamic being utilized only for Low end freqs. i would just go with the merlin as these two iems are almost the same price.
I removed the misbass hump in my IE8, by buring them in for 500 hours, turing the bass dial all the way down and upgrading to a TWag.... all three of these attibutes managed to remove the misbass, another cheap way to do it is to put tape over the bass dial, this way no air is allowed into the driver and it reduced the midbass a hell of a lot. then if you want slightly more bass just push a needle hole into it.
If you are still not satisfied, i would upgrade to the IE80, or upcomming IE800. The IE80 is said to have considerably less of a midbass issue than the IE8
Edited by Evilcalyptic - 4/21/12 at 2:37pm