if you want them right now don't get the m3 unless you upgrade the shipping to EMS.. i would tell you what the m3 sound like but i still haven't gotten them yet >_< the HJE900s are also good from the reviews but they're discontinued so might also be hard to find.
i don't have the j3 but i do have the s9 if they're anything alike... the slow write speed is due to the firmware.. it tries to keep files randomy spread about the flash memory so no section gets written over more than another to keep the flash memory lasting longer. so when copying files over to the s9 it's quite slow compared to everything else because of that.
it'll get there eventually... if you're on a time schedule should pay extra for the EMS. i got the m3 on preorder said it was mailed out 2 wks ago ,but hongkong post tracking doesn't even say anything.