I would only avoid it from things like those shops in food courts in large shopping centres.

If you know the shop I wouldn't worry. I eat sushi but only buy it from one place at my work that I know is flat out, and I've never been sick before.

I dont personally take chances with unknown places. I would rather be safe than sorry.

Speaking of which do you think Subway is ok? I've had some serious cravings for it but have been concerned as a friend told me to avoid it.
I still eat subway .... as for the sushi, I've heard so many different things and not being a fan of it myself I'm not going to be much help but as other posters have said if you know and trust the restaurant then it "should" be ok as long as the rice is fresh too