Although I would love a guaranteed drop at 320 light. I think a better way of going about it is if all items dropped within a +/- 5 light of your current light level. So if you are character is currently at 300 light, your drops will be between 295 to 305. Instead of the ridiculous way it is now with the light level drops of 280 to 320. Then maybe the rank rewards can offer a guaranteed drop that is at least higher than your current level.