Upgraded from 8.5 just last week to 10.0. Love it.
I’m in the grace period so will be able to grade to 10.5 at no cost.
I’m running Win7 and not about to upgrade that yet so…in all my other experiences of upgrades ( started on 6-6.5 and from there to 8- 8.5)
I can still run all of those versions straight off the desktop.
Now, more important than before, if 10.5 on my Win7 causes issues I’ll be wanting to just click back on the 10.0 icon (no reinstall ) and use it till I sort out Win10. ( could be months).
Is this how it works with this particular upgrade too?