For me the hardest part of IFR is getting the procedures perfect. I had most of my initial training in a basic flight-training device with a highly competent instructor. We went all the simulated procedures, emergencies, etc. to a point where they where second nature.
Once in the aircraft it was just to learn the different systems between each aircraft - basically getting familiar with them.
There is a big difference between hood time and actual IFR time but if the basic initial training is there, there should be no issues.
(edited for grammer)