You shouldn't lose any detail - all they have to do is copy a set of numbers into a file format the raw converter can read. There's no interpolation going on. The colour balance may be messed up if the embedded colour coords are wrong, but that's not a detail issue. I was given to believe that the compression was lossless, so it would be interesting to understand where detail loss can occur.
I too save all my raws in original form, but that's also to be free of Adobe's hegemony