I tried now to install QWT on Windows 11 23H2, and it behaved roughly like Windows 10. The installation first worked until the moment when the QWT services were started, which was not possible due to the same errors as in Windows 7.
Setting testsigning on allowed me to complete the installation, but left the system in a broken state which - up until now - could not be repaired. So W11 seems to be more like W7. So far, I could not find out what the missing dependencies are. Perhaps it’s the same for several Windows versions???
With regard to your question: That’s a difficult one, which probably has no simple, general answer. So I’ll try to collect some arguments that may have personal bias.
Omitting W7 from the supported Windows versions will affect those installations that require W7 and cannot be upgraded to a newer Windows version, due to applications not being supported there or, like in my case, due to special hardware, for which no drivers for W10 exist. (I have a high-resolution scanner needed for photographic work which runs under W7, but not W10.) It is difficult to say how many installations may be affected by this, but, on the other hand, there are installations with applications not supported by W7, but by W10.
The next aspect is usability. On my system, which is neither very fast nor very slow, there is a marked difference between the different Windows versions: W7 is acceptably fast, partially even faster than on a comparable computer where it is running on bare metal, but with a virus scanner. W10 is considerably slower, but you could still use it, with gnashing teeth. W11, however, is so slow that it is nearly unusable. All three systems have comparable resources allocated to them, so it is really a matter of efficiency.
This factor of efficiency extends to the UX. While W7 looks somewhat old-fashioned, it has a very efficient UX and allows one to perform many tasks fast and without much hassle, comparable to many Linux desktops. W10 has a much more unergonomic UX, often blurring the border between different, overlapping windows, and its menu structure requires much more navigating and scrolling. Finally, W11 is completely unergonomic, as well in its menu structure as in newly designed applications like the Explorer, which often hide the relevant options and features, while displaying a lot of stuff that is not needed for professional work, but can only be removed with a lot of work or not at all.
The next aspect is availability: Recent changes in Microsoft’s licensing terms and system requirements pose the risk that older versions of W10 and newer versions of W11 may suddenly turn out to be unsupported or require costly license structures.
Finally, the use of W10 or W11 may be illegal in some application areas in the EU, due to the telemetry functions in these systems violating the requirements of the GDPR, if personal data are processed. (In the documentation of Windows use under Qubes, I have suggested a way to mitigate this problem, but that solution may not be acceptable in many places.) So, if you are forced to use Windows, W7 may be your only option.
Using W7 poses a certain risk, as it is no longer supported by Microsoft, and the same will happen with W10 this autumn. But if these systems are run under Qubes, this risk is considerably lowered and may be acceptable. Furthermore, most attacks now focus on the newer Windows versions, so it may even help to stay with an older version - which, according to CVE statistics - has a much lower rate of security-relevant faults than W10 or W11.
Putting it all together: In my environment, I stick to W7 where I still need to use Windows, and where I have to move away from it, I try to switch to Linux and avoid W10 and, completely, W11. Clearly, this is not representative, but
may give some arguments to keep support for Windows 7. Running Windows 7 under Qubes may still be much preferable to running Windows 10 or 11, with or without Qubes.
