I too have two eR9 sets and have been suspiciously running well. I hope I don't jinx it.
Sometimes I am also amazed at how clueless most people are on basic bike maintenance. Though in all fairness, people who are willing to try LTWOO systems must be at least somewhat comfortable tinkering around the bike. LTWOO definite still have some works to do.
I have no doubt there are bad groupsets out there and that LTwoo's weather-sealing is subpar. Though why would anyone who's willing to pay over $1k USD for a frameset and probably more $$$ for a wheelset use a budget electronic groupset? At minimum I'd get 105 Di2 or Force AXS. LTwoo and Wheeltop at this point is for budget DIY'ers willing to figure things out while drinking a beer at midnight on the bike stand!
From my observation using this system, this is how I'd rate the reliability of LTwoo ER9/X components:
1. Brake calipers are surprisingly good though their proprietary mount sucks. At least you have the option to use Shimano mineral oil calipers.
2. Shifters are solid, tactile feedback isn't great, but they work. No real issue there.
3. Battery holder w/springs does the job, but needs to be properly secured in seat post.
4. FD is okay, not as good as Shimano. I'd use a chain catcher for added insurance.
5. Battery cables are flimsy and need additional weather protection. Room for improvement.
6. Most if not all issues from this groupset are from the RD going bad which is also the brains of the entire system. At least spare RDs are currently available for purchase.
7. Batteries. This will either make or break the entire groupset. Spend more than $10 USD and get something good.
I'd definitely use gear protection at all times and I'd only turn it off when fine-tuning the bike. 34t is the biggest I'd go on the cassette and only with a 50-34t.