I'm still running Studio 6.2. I've always been sorry when I moved to a newer version of Studio. Seems there's always a hassle getting going again.
However, I've been living with a very annoying issue for years and it would be worth moving up if it's been solved. (Someone from Atmel posted on this forum that it would soon be fixed when I raised the issue a few years ago).
If I program a device once using Tools->Device Programming, then close the dialog to make a code change, I can no longer reprogram the device. The tool is always busy. I'm forced to exit the application, and restart it.
This really slows down the compile/program/test cycle.
I'd like to give a newer Studio version a try if this issue is resolved.