That actually sucks to hear man. I was really hoping to grab an MM710 some day since this mouse is so promising
Although a bit heavy, seems like im gonna spend a long time with my G403... Just built like a tank.
You can make the G403 more lightweight if you remove the weight hatch, the magnets inside the mouse housing and paracord it.
I don't have a precision scale, but I reckon that will bring it down to slightly under the 80g mark.
I wanted to like the MM710, but it had too many niggles that annoyed me. Mine didn't actuate buttons if I squeezed it, it actually felt pretty well put together overall. The feet were pretty awful of course, they're not rounded and pretty thin like the Zowie ones, so either the housing or the ends of the feet scratched on my pad. I remedied that by getting some aftermarket feet which did improve the glide significantly (Tiger Arc 2), but then again companies need to stop trying to save $0.5 and actually put some decent feet in. Also not a fan of the silly feet shapes, I would have preferred something larger (a'la Zowie feet) or smaller (a'la IntelliMouse).
Cable I felt wasn't as good as people make it out as being, the braid on mine kept dragging on my pad, which kind of defeats the purpose, I'd prefer it if manufacturers stopped this braided silliness and just used a thin rubber coating, like the original G203 cable (very thin, malleable and light rubber cable, I prefer it even to aftermarket paracords; new G203 cable isn't as good as the old for whatever reason).
One more issue is the holes in the MM710, they're large and the sides have them too so holding the mouse was pretty difficult for me. I used fingertip grip and my pinky always sat on the edge of one hole so it was fairly annoying and fatiguing for my fingertips to grip it properly. I ended up taping up the sides because the hole texture was just so annoying.
I talked about the buttons above, but initially they did feel very nice and crips, shame the plastic just didn't hold up over time. I play some games where you have to hold down M1/M2 for a few seconds and the mushiness just was too much to handle.
Also the side buttons were annoying to actuate, not enough space between them to delimit them properly from each other making accidental actuation easy and the back button was too depressed in the housing, making it difficult to press sometimes.
If they improve on some of these niggles then the MM710 could be a fantastic gaming mouse, it just needs more robust clicks, slightly raised and better spaced side buttons, no holes on the side even if that adds a few grams, better mouse feet, a thin rubber cable. The Endgame XM1 does a lot of these things right, which is why it's so popular.