I believe the actual regen from C2 is 3500 mana in 350 ticks. It makes sense if you look at the natural progression of the ratios of max regen rates. I believe Gift of Pure Thought is also incorrect.
Breeze = 540 / 270 = 2 per tick
Clarity = 1890 / 270 = 7 per tick
Clarity II = 3500 / 350 = 10 per tick
Group versions
Boon of Clear Mind = 2160 / 270 = 8 per tick
Gift of Pure Thought = 3300 / 330 = 10 per tick
KEI = 21000 / 1500 = 14 per tick
Tranquility 12800 / 800 = 16 per tick
Be safe.