Update:​

So below is my review of my unit of the GK10. However, it has become clear that there are varying units and possibly QC problems. I would not recommend this IEM to anyone as long as those are not solved, and have therefore deducted a star from my initial rating of 4 stars. I like my set, but since there are multiple graphs going around and there have been reports of QC issues, be aware if you consider buying these.

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Intro​

I ordered the GK10 because I wanted an IEM with a piezzo driver in my collection, and I thought this one looked interesting. Unfortunately there has been quite a hype and anti-hype around them. It seems like you are now allowed to love it or hate it, and nothing in between. I feel like this is a rather unproductive situation and I hope the (anti-)hype around them will die soon so people actually get a good idea of this IEM.

I want to add that I am not a reviewer, I'm a consumer. I do not own a hundred IEMs, headphones and sources and I do most of my listening while I'm working.

Build and fit​

The build is decent for the price. It's plastic, but units look fine and they very light. The fit is excellent for me, I can easily wear these the whole day. I like the wood, but I would've preferred if the whole backside was wood because I don't really like the glossy plastic part. The cable is not necessarily great, but I've seen much worse. I haven't touched the provided tips because I have quite a few after-market tips

Sound​

I've let the GK10 burn in for at least 15 hours before writing my thoughts down. As source I've used the FiiO BTR5 and listened to music on Spotify.
The FR graph suggests that the they have a huge bump in the mid/upper-bass. I don't think it's a very representative graph for my unit, it does have a bit more mid-bass than I'm used to, but not thát much. I don't think they are dark or muddy, and I don't notice a lot of bass-bleed like the graph would suggest. That being said, I do think the IEM benefits from 2db less around the 125-150MHz (I didn't do this for the review though).
I think the stage and imaging is very good. Detail retrieval is also good and I haven't noticed much incoherency like I would've expected in a budget IEM with 5 drivers and three types of drivers.

Comparisons​

GK10 + Final Audio E vs Blon BL03 Mesh Modded + Final Audio E​

In short
The GK10 has better technicalities than the Blons, but I prefer the tuning of the BL03 over that of the GK10.

Bubbles - Yosi Horikawa
The GK10 has a wider stage than the Bl03. You can hear that the GK10 has more mid/upper-bass

Touch - Marshvll
The BL03 has more sub-bass, quite noticeable in the drop at 0:54.

You want it darker - Leonard Cohen
The BL03 handles Cohens voice better IMO. The GK10 has him more on the foreground but I find it a bit too forward on the GK10.

Sultans of Swing - Dire Straits
Snares hit hard on GK10 and they reveal the bassline more than the BL03. However, the BL03 sounds more natural to me and the voice is more forward on the GK10.

Never going back again - Fleetwood Mac
Plucked strings are crisp and snappy on both sets. The GK10 has wider stage and a bit better imaging, but the strings on the Bl03 sound a more natural to me.

Going to school - John Williams, Yo-Yo Ma
The violins sound more natural on the BL03, not sure if it's the tonality or timbre but I prefer them over the GK10.

Yours is no disgrace - Yes
This is a song where the GK10 really shines IMO. There is a lot going on in this song, and the GK10 handles it very well. Detail retreival is good, bass stands out and they are clearly fast enough. The separation, imaging and stage are very good. The BL03 also sounds pleasing, but doesn't have the technicalities to represent everything like the GK10 does.

GK10 + Final Audio E vs FiiO FH3 + Sony EP-EX10A​

In short
I like both, I think I prefer the FH3 just a bit over the GK10. They sound massively different to the point where it sounds weird when you go from one to the other, but I like the FH3 for some songs and the GK10 for other songs.

Bubbles - Yosi Horikawa
The GK10 is warmer than the FH3. The FH3 seems a bit more detailed to me, I feel like I can better hear the texture of the balls on the FH3 than on the GK10.

Touch - Marshvll
The FH3 has more sub-bass, quite noticeable in the drop at 0:54.

You want it darker - Leonard Cohen
Cohen's voice sounds better on the FH3 than on the GK10 to me. I feel this is a track where the elevated mid/upper-bass hurts the GK10.

Sultans of Swing - Dire Straits
Snares have more body on the GK10 again, I think this is due to the GK10 being louder in the mid/upper bass. I enjoy the song on both sets, they can both play it well but they have a different emphasis.

Yours is no disgrace - Yes
Both sets handle the speed and all the little details well. The GK10 sounds a bit fuller. I prefer the bass texture on the FH3. It's not recommended to keep switching between the sets, because the one I switched to always sounded a bit weird until I listened to it for a while.

Final thoughts​

I think the GK10 is an interesting set and I think it's a good set. I think the hype may have been a bit exaggerated IMO, since there are cheaper or similar priced IEMs I prefer over this one (BL03). I will definitely keep it in my active-duty box because I like listening to it and it's very comfortable. Does it "compete with $200" sets? Well yes, but there are $200 sets that are crap or are just not my thing so that's not really an interesting question IMO. I am glad I bought them because of the looks, the piezzo driver (for my collection) and because I quite like the sound. Due to the fact that I don't think the sound is as spectacular as the hype suggests and the talk about possible QC issues (due to the varying reviews out there) I would not recommend this to people who are looking for one IEM or have a tight budget; I would still choose the BL-03 over this one if I had to pick one.