The Yuin G1s took me by surprise because they retain some of the analytical properties of the small earbuds and mix it with a bigger bass and slightly warmer mids making the headphones more versatile. Where the OK1s had a tendency to be sibilant from time to time the G1s lesser treble intensity makes them more forgiving.
Overall the G1s provide a better compromise between definition and tonality than the OK1s because they are better suited for most popular music. Another noteworthy quality that the G1s have, is their sound stage. It is way bigger and resembles that of big headphones to a greater extent than the OK-series earbuds, which already had a good sound stage.
If you can appreciate a more analytical sound signature and are not bothered with using a clip-on styled pair of headphones and a small amplifier you should definitely look into the Yuin G1s.