Apparently, Microsoft did a great job protecting Windows Phone devices. Indeed, Microsoft has full control over the platform (Qualcomm) that is used by the different manufacturers of Windows Phone devices, so unlike Android there can be no sub-standard implementations here. As a result, all Windows Phone devices are roughly equivalent in terms of security. Until very recently, JTAG and chipoff acquisitions were the only methods to acquire most Windows Phones. However, in January 2015, Cellebrite implemented an acquisition module enabling investigators to perform physical acquisition of a lot of Lumia devices. The technology is still at an early stage. There's still a lot to do in parsing the contents. However, the filesystem is NTFS, and the OS is very similar to Windows, so eventually, this will be done.
Since then, yet another development emerged. Windows Phone Internals (http://www.wpinternals.net/) developed a bootloader unlock method for Lumia 520,...