"Of course now M$ have removed the WEI from Windows (since 8.1 if I recall correctly) so I cannot compare Windows 10 in WS 9.x/11.0".
On a technical point, a WEI stand-alone executable is still accessible from numerous sites (I think the front end was removed but not the engine). Since testing would be in a VM only, it's almost irrelevant if it's not part of "usual" current Windows, for your limited purpose. But be aware they might rescale it depending on detected OS and platform, I would run 3 tests not 2: WS9 using WS9 vm model, WS11 using WS9 vm model (not upgraqded) or checking same drivers, and then WS11 after upgrade to latest hw model. Just in case there are other factors at play.
Find your Windows Experience Index scores in Windows 8.1 - CNET
WEI Tool Brings the Windows Experience Index Back to WIndows 8.1
Unearth the Windows Experience Index in Windows 8.1 with PowerShell - TechRepublic
Having said that ..... the better answer is probably, don't use WEI at all. I would find an assessment based on WEI very dubious - I'm not even sure its comparable by much, there's no clarity what went into each number exactly, and no clarity how much real-world difference or scaling difference is signified by any changed results. WEI just gives you arbitrary numbers and little clarity how much any differences mean or even what they signify. It's also very hard to know what to target for improvement or what functionality to criticise. Use a proper benchmarking program (SiSoft Sandra, Passmark, Furmark for 3D, etc) - there are several reputable free ones around. Programs like these will actually test repeatably on different hardware, and give you hard "before/after" data component by component, so you can see the exact components of your system and its performance that changed, and by how much.
Hope this helps.
