I am Silver,
 from China and have 15 years of working experience in carbon fiber wheels. I also have my brand's serenade bikes. I am willing to share some experience with carbon fiber wheels.

Better stick to all steel cassettes

Why not buy both models (0 and 20). A seatpost costs around 50-60USD;  On short saddles (approx. 245 cm), you have fewer adjustment possibilities compared to a 275 cm saddle

Thanks! I've made some quick calculations on https://www.bikegeocalc.com and I'm going for 0 setback and 100mm stem. It'll still be more aggressive than the bikes I have but should be fine ahaha. Let's hope. Fingers crossed.

Let's see now how long it will take to deliver

Thanks. Unfortunately it's quite hard for me to assess since my other bikes are completely different ahah. Will try to get access to a canyon ultimate L size. Apparently they have very similar geometries.

I'm pretty comfy on the endurace for example L size, which is basically the same of all endurace. I know this one is more agressive, but just wonder really the difference on those 2 things. 110 stem and the seatpost setback. Bike size is definitely the 58.

I can imagine though thst with 0 setback I can still play with the seat sth like 15mm back. Will see but place the order in any case.

Why not buy both models (0 and 20). A seatpost costs around 50-60USD;  On short saddles (approx. 245 cm), you have fewer adjustment possibilities compared to a 275 cm saddle

I'm using Skywolfeye 14500 Battery 1200mAh Li-ion 3.7V Rechargeable batteries and they've been working great.

https://www.ebay.com/itm/155465836365

I do wonder if batteries make a difference with some of these bad ER9 groupsets? It's the only major variable besides environmental conditions and riding style (race, commuter, etc.). Perhaps bad batteries could cause RDs to fail?

Yes, I can confirm the batteries are an important part. The issue of not being able to charge for more than 10 seconds immediately changed after replacing them. During the fixing process, it was also quite obvious that the charger is quite important. I had multiple rides in a row where the derailleur died mid-ride (even though charging them during the night). I will circle back after the next couple of rides to see whether the issues continue.