A friend broke his er9 shifter, he crashed on it, so ordered and installed a new one (vs a batch from 2023, probably one of the first ones). The bleed screws are now bigger, and the shift buttons click more (feels like the new button has more travel for it to click and the button is less rigid (which makes sense if you have to travel more for one click).
Newer ER9 RDs have died much less frequently than the 1st batches.
They modified the tab / spring system in the battery very early on after people reported the tabs made the battery die.
Given LTWOO designs and manufactures everything in China, and all the above, it's evident that they make changes to the product on the fly, unlike Shimano or SRAM who have strict product releases schedules for lots of reasons, from marketing to the fact that they aren't on the factory floor, but on another continent. There's no list tracking the changes that i know of. I assume that when they make a change, it's for the best.
So, all else equal, probably best to buy new stock than old. Especially if it's like Aliexpress from a "reputable" store (not one with a random name full of numbers, I guess) vs second hand on ebay or something like that.
We can also assume that Chinese groupsets will converge faster with Shimano SRAM because users are guinea pigs and it's in their interest to do iterative updates constantly, so it may take them 1y to address 20 reported problems, when it may take 3y for Shimano to do the same. We also shouldnt be surprised that Chinese groupsets fail more at first, for the same reason. It's easy for them to modify something that breaks, so makes sense to spend less time testing prototypes ahead of releases. Dick move, sure, but rational.
After 11k km on the er9 (i'm on my 2nd RD), i need to do maintenance on my calipers, my front brake is noisy (disc rub), something must have moved and i wonder if the pistons are getting sticky, my rear brake is weak (I changed the hose and used a basic one, i think it's the problem), and my right shifter is shifting worse, in the sense that if i dont click exactly in the right place, sometimes it doesnt shift. If i were racing, i'd have to look into it immediately. But i dont, so i'm not losing sleep over it.
