and i have the magnum/205 and 5.13, if i had to do it again i would seriously consider the atlas with 4.3 or 5 to one. one main reason is weight. and the size of the freaking 205. omg huge. and if you want to do front digs. a 205 is hit and miss from what i can see. some people can get it no issues, others its bound up just enough to not shift.
the extra gears are pretty cool but all i use is 205 in low front and rear to go to the trail heads, and once at the trail heads i engage the doubler making it 5to1. i dont use the 2.72 as my low because i have to shift the 205 front and rear into high.... then when i get to where i need the 5 to one i have to shift both of them into low.
my vote after all this would be keep d300 and just move to 6 something axle gears. and wait for the atlas, you may not even need drive shafts because they are so close to the same size.