Well, one thing is that I completely agree with you that the gaussian blur in PS simply cannot create blurs like the ones the actual lens creates.
The warm lighting on the flower is beautiful. The overall exposure is very appealing. Really liked the 50-50 divide in the BG.
Just wondering if increasing DOF to bring entire flower in it (to make the whole flower sharp) would have made it better...??? But again understandably you would not have got this BG blur.