The simple fact of the matter is that no steel is an all-around "upgrade" of any other steel. They all have strengths and weaknesses, and every single one makes tradeoffs to excell in a particular area.
I like D2 very much--it would not be my choice on a blade this size. This knife is not ideally suited to chopping/limbing, but with the full-tang, slab grips and 3/16" stock thickness it is none the less built as more of a hard use utility blade than a pure cutter, and the advantages that D2 has over 1095 in terms of abrasion resistance and deformation resistance will not shine out in such use. As others have said, it is far more likely to chip and fracture under heavier uses.
Now certainly, there is the camp here that believes that chopping or other "rough" use should not be the principle consideration in selecting a blade steel, and they're certainly as entitled to their opinion as myself. However, if all the knife is ever going to be used for is the same type of slicing tasks that you could use a fillet knife for, why not just buy a fillet knife which will--regardless of steel type--slice circles around the RAT7 due to far slimmer blade geometry? No--a knife of this size and weight (I'm not saying it's heavy, just far heavier than a fillet knife) is intended for more than just food prep, whittling or skinning.
Given the design, I think D2 is a step backwards from 1095--now, on the smaller knives out of this series it'd be a different story, as their uses would likely be relegated more to straightforward cutting.
Be sure to let us know when you decide.