For me power is cheap! Also I would go with the 4770. Yea you don't need the HT but it has 8MB L3 cache vs the 6MB L3 of the 4690K. That cache should help with the larger FFT's
Also don't get misled by typical power usage. Prime95 is anything but typical. You need to be looking more at max power. Haswell has much better idle power than the previous two generations but max power hasn't changed much. The speed settings of released Intel processors has more to do with fitting the max power into a specific envelope than what the processor is capable of running at. One reason why they overclock so well. If you really want to compare system power per watt I can connect a power meter to do some measurements. Two systems will use more power than one but it is about the power per workload unit.