OK found time to assemble the thing.
I got a unit which came with fw 20180702 (Jul 02) that is the last stable release.
The good: it works
The not-so-good: emulation was so-so (nes 1942 had gfx glitches for example and I could see slow-down here and there and the screen scrolling was "weird" as if you can see it redraw)
The ugly: I botched the FW update as I thought you had to go serial with the FW, wasted 45mins and then just tried the latest firmware (which changes the procedure by the way ... aaargghh) and took me another 10mins to figure out where to put the actual emu pack as that is no longer part of the upfront flash procedure (there's a small note in a post in the forum ... sigh).
Anyhow updated to fw 20180727 and go-play.fw pack 20180726, this fixes the NES issue, many slowdowns seems gone and because they swapped the SMS emu they got CV support as well AND (not sure they know as they don't talk about it) if you suffix your SG1000 games to .sms they work too (with weird palette like a real SMS). The CV requires a BIOS to work (another 5 minutes lost in figuring out wtf it hanged).
Judgement: call me impressed given the type or processor it has I was expecting much worse, I don't think it'll ever move out of the 8bit emu realm but so what!
BONUS: you can program thins thing as an Arduino and control speaker, led, display via Arduino IDE, gosh it's on BT so you can even control it via a phone app ... and it seems it supports micropython ... it's really cool for what it is.
Should you drop any other other portable emu you have for this one?
No, I believe a PSP runs circles around this thing, but for what it is is very nice, the screen is good, the speaker a little too loud even at minimum setting (no wonder on the website Hardkernel teaches how to replace the resistors to make it quieter).
I am happy with my purchase but they need to ship it with the new FW as the procedure to update the emulators is all driven via SD, even if in the last month alone they changed the FW many times and 3 times already the change required to flash the thing with their tools (they are not bad per se but not exactly user friendly and given the instructions are for the last stable release it's a little too hard for the uninitiated, but there's a forum that somewhat tells you what to do).
Also pay attention when assembling it, apparently it is very easy to crack the display, and I thought it should have been easier to latch the LCD flat cable to the motherboard, the speaker cable also has some placement issue (it's too long).
DO I LIKE IT? HELL YES.
WOULD YOU LIKE IT? ONLY IF YOU CARE TO TINKER A LITTLE (it's a solderless DIY kit for crying out loud)