I have always put fat cap down with no water pan in my GF and they have turned out fabulous. 225 degrees also.
I usually get a little impatient at the end of the cook and bump my heat a bit because the meat stalls for such a long time and I wanna eat at a reasonable hour after the meat rests about an hour.
I do render down the fat in a small pan below the brisket , but I am not sure if it effects the moisture.
Also I wrap at about 155 deg F. in peach paper (fat cap down) . I use some of the tallow to mop my peach paper, which locks all the goodness (juice) in and still produces nice bark.