I have a 1520, preordered from AT&T and I love everything about it!! Coming from a 920, the screen is absolutely fantastic and the microSD card is a huge plus. I have big hands but it still took me quite a bit of time to adjust to the bigger size. I was able to do everything one-handed with the 920 and that is the one thing you will NOT be able to do with the 1520! So, you have to ask yourself if that is important. Since I already have the 1520, like you said, I could never go back to anything smaller regarding screen size but If the 930 had come out the same time as the 1520, I'd really have a difficult time choosing between the two. Also remember that the 1520 comes with an IPS LCD display and the 930 comes with an amoled display. Your 820 is also amoled so you may find the 930's screen will have the rich, saturated colors you're used to.
So, ask yourself... one-handed operation & 5" amoled display or a microSD slot & 6" lcd display?