Just thinking out loud and wondering - the D7100 looks Superb in almost every department, could it be the Best DX DSLR when comparing IQ and AF ability? i know people have mentioned its buffer rate - but if you are like me and shoot one shot at a time then that does not matter, its additional crop feature looks very good also as long as it is not creating any further loss in IQ or increasing noise, i once had a bridge camera that had a similar feature and called it a digital zoom convertor, but messed up the IQ by adding pixals to extend the zoom/reach.
P.