The FAA IR was much harder than the JAA IR but I did it because I was flying 2x a day for 2 weeks, and the checkride was right on the 13th day. This level of currency makes "everybody" very good and minimises costs.
I suggest that had you done a JAA/IR first then you would have said the JAA/IR was much harder than the FAA IR. You're right, its all about the degree of currency and experience. Starting an IR is always a tough learning curve. From memory your IR is a single IR, again that is much easier than a multi IR. I speak from experience of teaching both.
Both FAA and JAA systems for the IR have quirks, merits and disadvantadges, I could not hand on heart say one is better / easier than the other.
Both allow you to to do a journey in IFR conditions and to have the skill set to decide if that journey will be safe due to limitations such as the aircraft or weather.