From my experience, they sound much cleaner after about a day.
Bass wise, I havn't heard the MG7, but from my other experience with dual dynamics, the impact/punch should be similar, but the texture is behind. So for a bass centric song, it won't sound as good, but for general pop etc, it definitely sounds good.
I also have my w4r with me, the 846 definitely sounds better, especially bass impact, where you can only hear the impact on the w4r occasionally.
Take a look at the comparison between 846 and w60 on earphonesolutions, I decided not to wait for the w60 because the 846 sounds more fun. But apparently w60 has better mids and very similar bass with a laid back signature.
Thanks for the heads up on the review/comparison between the W60 and the 846. If it is accurate and Earphone Solutions was very accurate with their reviews of the 846 last summer there is one other factor to consider. With the 846 you can change filters to suit your sonic tastes whereas all you can change on the W60 is the faceplate.