Another masochist eR9 beta tester chiming in:
As with the user above I also had sub-optimal interactions with their customers service, with typically 1 business day gaps in the reply time, so getting a replacement part which I had damaged took a total of 5 days to be dispatched.
Regarding the shifting performance, it's quite good. A few rides so far and no missed shifts or issues with the groupset not waking up.
Shifting under load up to 200w is crisp and the app integration is very good. Being able to adjust each cassette and chainring offset through the app is fantastic for setup, during my first ride I was able to whip the phone out and fine tune the trim whilst riding.
Regarding the trim function, I'm not sure if it is a result of the latest update but you can now trim in both directions (however) the trim direction is not controlled by the user. Essentially whenever you hear front chain rub, pressing shift again will trim the FD if the system determines it needs trimming, and there seems to be several steps. I.e if I shift from the 11th cog to 9th there is a trim step, then 9th to 3rd it will trim again, then the same the other direction.
Install wise it was easy, not having to run gear shift cables saves some grey hairs especially if you're fully integrated. The YouTuber Klein concept has a solid 90min install video which walks through all the steps.