Well, for all genre, I am not sure. I do think the it lack some impact in bass for ROCK and RAP.
For me, it is perfect for high quality recording like jazz, classic and vocals. But, for normal pop and rock, there just not enough impact at the low side. There is nothing wrong with sound quality and bass control, just not punching enough to make me shake my head.
Even my TF10 does better on the rock side than Miracle. I guess, you have to drive it with a very dark amp to get the full satisfaction on bass.
Other than that, it is the best IEM I have ever owned. (Coming from SE530, IE8, UM3X, ER4P and EX700)

Alan, this is based on my returned Miracle, fit is perfect. I hear only what is in the Recording. If it has bass you will definately hear it.
Its a very versatile IEM. These things are Like a Well tuned machine If you feed it low quality recordings then you wont get its true potential. These are as you know a step above those other IEM's, I have ER4 also but it's not in the same league. You raised amping...Yes good point, I tried with ALO RX-II & III and it steps up to another level , they seem to scale up very well resulting in Thunderous bass. But again IF it is on the Recording. Thanks Alan good to hear you have one also. Might want to try a Merlin one day.

Well，I am not a bass head, otherwise I wound went for JH16 or UE18. The thing is, I am using it not only for my Guitar, but also in a daily bases with portable devices. Thus, listen to some mp3 pops is unavoidable. The main reason I get this IEM is to hope they are tuned with more forgiveness to the recording( with an HD800 sitting at home, you know what I mean by harsh sibilance and unfocused vocals in mp3s.......... ), I guess I just need to find a better portable player and see if it helps.