I decided to start solo mining on an Antminer U3! I am using CKPool to do it and I'm using my Raspberry Pi as a controller. This is my stats so far:
{"hashrate1m": "67.3G", "hashrate5m": "63.7G", "hashrate1hr": "58.9G", "hashrate1d": "9.64G", "hashrate7d": "1.53G", "lastupdate": 1449912061, "workers": 1, "shares": 219756, "bestshare": 514557.60289778293, "bestever": 514557}
It has been running for 4 hours and cgminer says the difficulty is 50.

If you want to watch my stats: http://solo.ckpool.org/users/1MEWxQE7nyX5rTsnQxr9NmFdCVdMZQ5fkz
And I see what people mean when they say the U3 is unstable. The hash rate is varying between 50 and 68 Ghash/s (according to CKPool)