Видеозахват с нонеймовской web-камеры (отдаёт картинку в формате YUYV):
Raspberry Pi

320x240 - FPS 2
160x120 - FPS 11

BeagleBone Black

320x240 - FPS 4
160x120 - FPS 18

Результаты opencv_benchmark на RaspberyPi Model B (от LoAP)

/ Linux 3.6.11+ / OpenCV Version: 2.3.1

[i] file name: image.jpg
[i] channels: 3
[i] pixel depth: 8 bits
[i] width: 320 pixels
[i] height: 240 pixels
[i] image size: 230400 bytes
[i] width step: 960 bytes
cvConvertImage 3.201174
cvCanny 27.452606
cvSobel 11.490731
cvLaplace 57.239189
cvIntegral 8.683088
cvExtractSURF 3273.248047
cvSmooth 13.342096
cv::FAST 25.508913
cvGoodFeaturesToTrack 100.097366

$ cat /proc/version
Linux version 3.6.11+ (dc4@dc4-arm-01) (gcc version 4.7.2 20120731 (prerelease) (crosstool-NG linaro-1.13.1+bzr2458 — Linaro GCC 2012.08) ) #456 PREEMPT Mon May 20 17:42:15 BST 2013

Результаты opencv_benchmark на BeagleBone Black (rev. A5A)

model name	: ARMv7 Processor rev 2 (v7l) / Linux 3.8.6 / OpenCV 2.4.2

cvConvertImage 		2.119352
cvCanny 		13.427492
cvSobel 		3.507087
cvLaplace 		70.910233
cvIntegral 		4.202680
cvSmooth 		6.564841
cvGoodFeaturesToTrack 		115.395218

cpuinfo

RPi

cat /proc/cpuinfo
Processor       : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS        : 697.95
Features        : swp half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xb76
CPU revision    : 7

Hardware        : BCM2708
Revision        : 000f
Serial          : 000000002a176d59

BBB

cat /proc/cpuinfo
processor       : 0
model name      : ARMv7 Processor rev 2 (v7l)
BogoMIPS        : 990.68
Features        : swp half thumb fastmult vfp edsp thumbee neon vfpv3 tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc08
CPU revision    : 2

Hardware        : Generic AM33XX (Flattened Device Tree)
Revision        : 0000
Serial          : 0000000000000000

Ссылки
Beaglebone Black — Box to Bot — есть табличка сравнения с Raspberry Pi
How to Choose the Right Platform: Raspberry Pi or BeagleBone Black