Weird, switched to bfgminer 3.5.1 and the reported error rate was way down:
BPM0 | 5s: 2.21 avg: 2.21 u: 2.09 Gh/s | A:2431 R:16+1(.69%) HW:350/3.5%
BPM1 | 5s: 2.30 avg: 2.30 u: 2.17 Gh/s | A:2407 R:17+0(.70%) HW:382/3.7%
BPM2 | 5s: 2.29 avg: 2.29 u: 2.16 Gh/s | A:2465 R:12+0(.48%) HW:408/4.0%
BPM3 | 5s: 1.99 avg: 1.99 u: 1.88 Gh/s | A:2148 R:19+0(.88%) HW:312/3.5%
but now after flashing the firmware on the furies, they're back up again
BPM 0: | 2.29/ 2.29/ 2.18Gh/s | A: 81 R:0+0(none) HW: 26/7.0%
BPM 1: | 2.21/ 2.21/ 2.19Gh/s | A: 79 R:0+0(none) HW: 72/ 17%
BPM 2: | 1.99/ 1.99/ 1.89Gh/s | A: 70 R:1+0(1.4%) HW: 44/ 13%
BPM 3: | 2.31/ 2.30/ 0.51Gh/s | A: 18 R:0+1(5.3%) HW:265/ 76%
and one of them is again being stubborn about giving good performance... I need to learn to leave well-enough alone.