Strange as it may seem, the CAA side of experience was quite positive for me
The PA28 in question still had its ARC valid for 10 months, and when the UK CofA was issued, the French ARC was simply stamped and sent back to me. No survey/inspection ensued, even though the forms and guidance suggested it might. Just a lot of details to be given on the form to request the UK CofA, including the CAMO company, but that I had already arranged by the time of taking delivery of the aircraft.
No Export CofA within EASA-land.
PM me for more details if you wish.
/h88