The GR07 cable is not replaceable but quite good. I haven't heard of any problems with them. It is actually a tough call between the GR07 and the IE8 even at half price. If the cost were the same for both (or close enough), buy both! But if you like warm and bassy, go for the IE8. If you like a little more neutral, go for the GR07. The sound stage is def better on the IE8. If someone offered me either brand new, I'd pick the IE8 because it has the replaceable cable. Sonically, I'd pick the GR07. Yup. Its that good.
Now... I don't want to make this an iem recommendation thread!
Just a quick question, how is the cable on the GR07? I have, to date, not had a single portable earphone/headphone that hasn't died due to a cable after a year or two. They have all been cheap though, a bunch of PortaPros were the most expensive ones. Guess I'll have to make good use of the case otherwise.