I haven't tried balanced cables - it's a source of great debate (there are some older threads with some very technical information from some very knowledgeable sources), but there have been some cases reported of balanced cables with the 7500 and 7700 being a very effective way to cope with ground loops.

As for the firmware on a new 990, I'm not sure. A couple months from now, it's very likely that the units being shipped out came from the factory after the firmware was given the Outlaw seal of approval, in which case it'd already have that firmware installed. A call or e-mail to the Outlaws would let you know for sure, of course.