The topic is kinda old, but I'm writing for those who want to try this way since I recently did it myself.
With EASA SEP PPL (Czech CAA) and FAA 61.75 PPL it's perfectly legal and possible to get the FAA IR. I did mine in about 1 month (including waiting for a checkride) - from my point of view, it was more difficult than in Czechia due to traffic, precision maneuvers and different phraseology. It was considerably less expensive though.
But then I was not able to apply for an EASA IR right away: the requirement is 50 hours PIC under IFR. The other option is 15 hours as a PIC under IFR and 25 hours with EASA FI (some schools in Florida are ready to provide the one for you), that can include 10 hours in ATO, but I didn't like that way. FAA dual hours do not count since in the EASA world dual even with FAA PIC hours means non-PIC. I keep two separate columns for EASA PIC and FAA PIC time: EASA PIC means that I don't have an instructor in the airplane at all, FAA PIC usually means that I'm on the controls regardless who's in the right seat.
Since I wanted to do my CPL as well, those 50 hours can count as my timebuilding, so why not to fly them under IFR? And US flight hours are much less expensive, especially in an IFR-equipped aircraft.
Then I went to Europe again and enrolled into CB-IR course. By that time I had all EASA ATPL subjects passed, so I did not require any theoretical skills assessments. Basically I could even directly contact the CAA for the exam, but I considered that it's better for fly in the EU airspace in an ATO to get familiar with the procedures and learn differences. It took about 10 flight hours (my ATO's policies required that amount). That was enough for a successful practical skill test and a standalone IR+PBN. Not a restricted one but a 'normal' EASA IR.
So there are only 2 ways for a FAA IR holder: one is 50 hours PIC IFR (hours during FAA IR training do no count), the other is 15 hours PIC IFR, 10 hours in an ATO, 15 hours with an EASA FI (can be in ATO as well). Of course I'm talking about the minimum requirements.
After that you can have a EASA PPL with IR and a FAA IR based on a 'piggyback' 61.75 FAA PPL and at least 120 flight hours (probably up to 150). But it's worth to mention that FAA IR rules are not 'more relaxing': you need approaches in actual IMC or 'under the hood', and if you don't have them, you have to undertake almost the same procedure as EASA IR revalidation/renewal. But I totally agree with all other mentioned benefits.
Talking about the risks - you have to maintain your 'piggyback' FAA PPL and revalidate it every year. I solved this problem by obtaining a standalone FAA CPL. Anyway the most expensive part (but also the most exciting) is gaining a flight time, and doing it mostly in the US seemed much better for me.