I would definitely make the move to 15'' wheels with the 33x10.50. In that particular tire, the 285/75/16 weighs 10 lbs. more than the 33x10.50. Also consider that the 285 is a load range E tire while the 33x10.50 is load range C. All depends on what you are using them for. I can tell you that I had 285's on my TJ and couldn't wait to get them off.
If I still had my TJ and wanted to go to a 15'' wheel I would strongly consider the American Racing Mojave Teflon. They have a utilitarian look to them without being a heavy steel wheel. In fact the 15x8 weighs in at 19.5 lbs. while you're Moab wheels weigh in right at 25 lbs. Pair them with the 33x10.50's and you're talking about a 15lb. weight difference PER corner. 60lbs. total unsprung weight which is just like throwing 120 lbs. of gear in the back of your Jeep. That is a big weight difference that I guarantee you will feel. The lighter weight combo will put much less stress on your brakes and steering components and of course not zap nearly the amount of power that the wider tires will on the stock alloys.
Here is a pic of an XJ with those wheels and the BFG's. Not sure of the tire size though.