Windows 10 BootCamp Drivers Would it be harmful to my rMBP if I installed Windows 10 when it is released?
I was talking to someone about it, and because Apple uses non-standard hardware voltages could cause damage using the drivers for Windows 8.1
I am currently using Windows 10 TP (Technical Preview Build: 10240) on my MacBook Pro Late 2011. I am using Boot Camp with the drivers made for previous Windows versions. I haven't had any issues with using it but after upgrading to an newer build I was needing to reinstall the driver package again to get it to work properly.

Also, as Steve Chambers said in his answer, it won't physically break or damage your Mac. Only remember that if you are upgrading from a previous Windows version, make a backup in case you need to go back or do a clean install. In addition, it could be a good idea to have the Windows drivers ready on a USB flash drive just in case.

This is tested with the latest TP (Technical Preview) build of Windows 10 but could change in the final version (unlikely but could). If you are not in a hurry, wait a week and then do a Google search and see if anyone had any issues with using the released Windows 10 version on Boot Camp.