Unfortunately, I neither have a clue what this IEM is nor who the Vsonic is, but according to the manufacturer's website, GR07 is a studio-monitor flagship model, equipped with a driver which has a bio-cellulose coated on its diaphragm. As far as I can recall, there has been only one earphone with that technology implemented in the history of headphones: A good ol' discontinued SONY MDR-E888. How interesting.
PRO: Very good built quality with an uber distortion performance. This is the lowest I've seen from an IEM. A nice gesture from the manufaturer to ensure users' wearing comfort: Not only GR07's stems are pivotally adjustable, the IEM comes with whole bunch of ear sleeves. The impedance characteric is very stable too.
CON: The polarity is inverted; not a flagship-quality. GR07's spectral balance somewhat reminds me that of SONY MDR-EX1000, IMHO. And obviously, the rated frequency limit of 30,000 Hz is just NOT TRUE.
ON SECOND THOUGHT #3: As mentioned, GR07 is almost free from the electric damping issue, which happens to be very problematic with some IEMs. Even a 100 Ω resistor does not alter the frequency response of GR07 at all.