I don't currently run a dual boot environment on any of my PCs, but at one time in the past, I have 4 or 5 operating systems spread across 3 machines.
I had XP, because at the time I was testing some bespoke apps for a client, and they would NOT run in a virtual machine, I needed real, accessible hardware resources to make it run correctly.
At the same time, I had a dual boot on the same PC running Win7, for testing a release of AutoCAD before it hit the live CAD environment one of our clients operates. Again, this will not run in a VM and requires a lot of hardware resources to run
On another machine, I had Ubuntu and OpenSUSE loaded seperately to test the GNU and KDE variations of some apps before release to a client that uses Ubuntu 10.04 LTS on a bunch of their end-user workstations.
And finally, I had a hardware test bed that was loaded with XP, 7 and Win10 tech preview. The only reason it had win10 on it was curiosity
a lot of the machines I've used for work and play tend to be AMD, so the virtualisation tech is very limited, especially on older systems. We also didn't shell out the money for VMWare at the time and most of the free apps for virtual machines kinda suck IMHO, not to mention you can't technically use them for business under the EULA.