PAL IS 25 FPS & NTSC is 30 NDF (or29.97 DF). In order to make 30 FPS into 25 there needs to be compromises. I believe you can do it in Compressor, but I would think it would be best to burn a DVD-R with open region coding. They should be able to play it in EU. I've sent many NTSC DVDs to EU with no problems. As long as they are played on a recent player (last 5 years).
Ask any post house in the LA metro area what they charge for standards conversion & find out how difficult it is. I'm not saying Compressor does a bad job (I wouldn't know personally), I would just be worried about how many frames it is discarding, especially if it is progressive with 3:2.