I read somewhere that I would need heads for hvm sysnet
Wherever that was, it was false.
There is a R4.1 report by badgateway remarking that “Ethernet needs Heads v0.2.0-1148+” That is an edit by me. The original actually said “Ethernet interface did not work until HEADS was upgraded to current version.” and the BIOS version reported was “CBET4000 Heads-v0.2.0-1148-g4b26007-dirty” (that Heads version looks rather antiquated to me).
When HCL reports are submitted I can edit them to make them formally correct, but I cannot evaluate the claims made within. This particular report was for model 23252SG. One scenario I can imagine is that this particular machine already had an earlier version of Heads installed, which might have caused an issue.
Compatibility is fine.
Heads may be desirable, but it is not necessary.
In addition to @unman’s experience one can also draw confidence from the fact that Insurgo’s PrivacyBeast X230 as well as the NitroPad X230 are based on the X230.
To add even more, there is another R4.1 report from Amir for the 2325PB3 model running Heads v1.3.1.
Maintaining the HCL for some time now it is my totally unscientific impression that the ThinkPad X230 is likely the very best supported machine for Qubes OS.
In case of R4.0.4 it is also on the list of community recommended computers