I don't know what to say, my ER9 is still working great. I use the whole gear range as well sprinting flats, hill climbing and fast descending. I rotate my 3 bikes, so it gets used every third ride. No issues with battery drain and I top off my batteries all the time. I'm almost tempted to get another groupset for my other road bike.

Maybe I'm just lucky or I'm using the right combination of batteries and app settings to keep it from imploding on itself!

More likely a QC issue affecting a large number of products from the same batch, even if a QC issue by an electronics supplier to Ltwoo and not necessarily by Ltwoo, itself. Also could be a possible design issue that was either solved or weaseled its way in through later design changes. Iterating the design quickly within the same model and model year could lead to all sorts of issues being fixed or un-fixed without any way for us to easily tell.

Exactly this. It's one of the few known brands out there that doesn't look like everything else. Their curved shapes - you either love or hate, there is nothing between. But even the most dogged haters must admit - they are at least unique.

The UCI can go to hell for a lot of reasons. but the biggest is the standards/guidelines for race bikes. These extremely limit creativity of road bikes. its like the cafe standards in the US for cars/trucks... its the reason we have these huge trucks that are a ton more dangerous.. And so these limited styles get past down to all the other levels of bikes. pinerellos like to push design boundaries. look at a lot of the mtb designs. they get interesting. If the UCI doesnt change standards. I fear we are going to see a significate drop off of interest in road bike as a sport. I already see a drop in the number of road riders in my area.

drove about 1500 km on mine
it was necessary to replace the compression cap with a specialized
otherwise everything is fine

Dub delrin spacers are good for this use. Fairly easy to cut and at ~29mm they are a pretty close fit in size. I recommend using just 1 if you can.

Update. On 18 May, the 3rd er9 RD died, and i contacted my reseller. 24 May, i contacted my reseller about my own er9 RD, because there are clear issues with recharging. Long story short, charging it, more often than not, results in the battery actually discharging. Go figure. I have a standalone lithium battery charger so i'm now using that until i get a replacement. I know a thing or 2 about lithium batteries, and i tried several different batteries (the actual Ltwoo battery compartment) as well as several different sets of lithium batteries, in various states of charge: the problem isn't coming the lithium batteries.
May 30th, still no resolution on either of them. my reseller makes it sound like ltwoo is being difficult this time around (for the previous 2, they were more straightforward).

The previous 2 broken ones (contacted my reseller on 17 Apr), i still havent received (it's not entirely ltwoo's fault, because they're in a box with a new wheel, so that took time too, but still, that box has been in transit for almost 20 days now, and i still have no idea where it is. So 1.5 months and still no replacement.

My friend whose RD died on May 18th had a triathlon the following weekend. He's back on his older sworks di2, at least the er9 died on a casual training ride and not on race day...

We're all loving Chinese groupsets in my cycling group, and the behaviour of ltwoo makes it extra tasty.