Great news. Thanks for all those comments!
What are the specific issues you have read about...?
It's mostly about slow boot times. I found also a report of a SATA drive having this issue. But it seems to happen or not- depending the particular configuration.
There's a great article about the interaction of APFS und TRIM :
Caring for SSDs: TRIM, wear levelling and APFS
I decided not to enable TRIM (on Mojave/APFS). It seems to be unlikely that issues will come up with recent SSDs, as they manage wear leveling by them self good enough and the implementation of the TRIM command under APFS/macOS is not very well known.
Regarding the "870-disappeard-after-warm-boot" issue I contacted the Samsung support and they concluded as follows:
"860 EVO and 870 EVO has different controller, what shouldn't be the issue, because Samsung 870 EVO is compatible with SATA III, II and I.
Today we tested the 870 EVO on SATA for a warm boot and it works fine on our system. Unfortunately we don't have the same system as you, in which case we can't verify if the problem is with the older generation Intel Core or with the SATA connector."
Not very helpful, but thought to share it here.
If I get new findings I will post it here.