We have a couple customers using IDEAS that export IGES files to us. I've tried to keep an open mind considering that the integrity of the native model plays a major role in export quality. With that said, I have to say that these files are some of the worst that I have ever dealt with. Hopefully the new UG/IDEAS release will correct some of this.
To be safe, before entering an agreement, I would request a trial transfer of data just to see what I would be dealing with. Third party services are an option but the cost could be major factor if you will be dealing with many files (and don't forget design changes & revisions).