Mine runs fine with 4 blades pointed at it. Has not missed a beat for the last 10 days.
I'll have to mess with it some more when I'm not in the middle of troubleshooting other things. When I had both the Cube and Blade pointed at the Rpi it seemed they both reported lower hash rates than when pointed at bfgminer on a Windows machine.
I've about 35GH going through mine, and it actually seems to run bfgminer a little better than the Celeron NUC running Windows. Though, only 24GH is going through the proxy, the rest is via USB, with more USB stuff due any time.
But, the USB is stuggling I think, as I'm forced to use USB2.0 hubs, plus the onboard ethernet is running off USB on the Pi. The "restrict it to USB1.1" workaround really nerfs the NIC's performance, so that might be a side effect some folks aren't aware of, especially if you're trying to run a proxy off the Pi.
I bit the bullet and ordered a BeagleBone Black today. I'm excited to see if MinePeon is released for the BBB. I'm willing to beta test it, wink wink nudge nudge. I'll be just running bfg off Angstrom in the meantime.
Added bonus of the BBB is that it runs off 5V, which should give a bit of load for the PSU - currently I'm using 12V exclusively.