Is it profitable for you? How long have you been doing it? Just curious.
He is not mining with rasberry pi, he is using it as a control board/ brain for the USB stick which does nothing but "hash", so you either run Cgminer on your PC or put it on a rasberry pi, the latter of course is more convient and consumes less power compared to leaving your PC on 24/7.
This whole set up is far from profitable, all of these cute and tiny USB miners are not profitable, you use them for fun, or to play the solo lottery or just to get the hang of how mining works, if you are interested in mining you need to learn about ASIC miners, those are noisy industrial-grade machines, and they happen to go up in price by almost a factor of 10 in the past couple of months.