IIRC, didn't the unlock in the San Bernardino case use an exploit(s) specific to the 5C or something? Also IIRC the iPhone 6 has some sort of hardware-level protection against this.
Even Apple does not seem to know what the exploit was, as they are pursuing legal options (or dropping hints to that effect) to compel the FBI to reveal it to them.
Cellebrite describes [1] the solution as working for iOS 8.x on the following devices:
> Cellebrite's unlocking capability supports the following devices: iPhone 4S / 5 / 5C, iPad 2 / 3G / 4G,iPad mini 1G, and iPod touch 5G running iOS 8 ...
[1] http://www.cellebrite.com/Pages/cellebrite-solution-for-lock...