I havn't discovered any instabilitie issues. The Board is running now (with these settings) for over 21days @ 100% load.
I'm running a self-compiled NEON-optimized Version of Einstein@home's GW-App(LowFreq).
Sure in order to get it stable at this high frequency, I had to ramp up the Voltage to 1.425V. Which is much above the recommended max. Voltage of 1.35V.
And I wouldn't recommend this (quiet dangerous) setting to any other user. Thats why I don't included a detailed discription in my post.