In my view there is no such thing as pros or cons in installing the Technical Preview of Windows 10. This is just a technical preview for testing purposes and not a complete roll out of the product.
Microsoft must be testing the OS for bugs and technical glitches with the help of developers. Moreover, every fresh installation of OS needs data backup followed by data restore after installation. That's why Microsoft recommends it to be installed on virtual PC instead. This is just a general advisory.
If you don't want to install it on a virtual machine, you can install it on any other hard disk partition in your PC and work along with currently installed version of the Windows.