Thanks for the info, Saab. I received a reply from StarTech customer services this morning to the effect that the model I was thinking of buying needed USB C connections on both computers and there had to be DisplayPort Alt Mode, which I'd never heard of. Only one of my machines had a USB C socket, so I regrettably had to forget their KVM, as they're apparently very good. Interestingly, they said that Windows versions had no effect on their operation, which is as you said. So much for the adverse reports I read.
I looked around for a JideTech unit based on your experience but there was nothing on this side of the Atlantic* and eventually decided on a Greathtech from Amazon (despite its ridiculous name) as it was only £30.00 and had good reviews from various sources.
It arrives on Monday so I'll find out first-hand.
While I'm here, after my first week with Windows 11, I'm Not Impressed. The navigation has been needlessly complicated by the 'bean-bag' developers and it'll be a nightmare for occasional 'mature' users who've gently moved through the previous Windows versions. And I still prefer MS Office 2003 compared to Office 2019 and its ribbon options. I suppose I'm a latter-day Luddite.
*Just seen that Amazon now have the JideTech in stock!