IMHO, IT seems that the real difference is not the difference in OS, it is the difference in file system. The other difference would be the character-set used by the OS.

Using You can always try ftping the files over and see if they won't if the file systems are different they probably won't work.

If you do the exp/imp option, you can do one of two things. You can pipe the exp to compress ftp it to the target node using binary then pipe it from compress to imp. You can also create an OS pipe to directly pipe it to the other machine. I haven't done the second option myself, however, Where I worked last they were using that option to clone a 1tb database from SGI to HP-UX.