Importing (at least from Evernote) is incredibly slow. It has an uploading phase where it uploads the ENEX file to the server, and then a very slow, long phase where it creates each individual note in the UI, at a rate of approximately 3 seconds per note (as observed in my import of a file containing 910 notes). During this time, I can't start any other imports. I've also been admonished to "not close the browser".
This is a problem for me, as I've got a couple of dozen files to import. At this rate, it's going to take me days to complete my import process, and I'm going to have to babysit it the entire time.
That doesn't seem right.
If I've uploaded the ENEX file to the server, couldn't the note creation be done on the server, without any UI interaction? And once the file is uploaded, couldn't I start another import? If it were done that way, I could upload a file, wait for the uploading phase to finish, upload the next, wait for that one, and so on. Once I'd uploaded all of my files, I could walk away. At some point, they would all be done processing, and all of my notes would be ready for me.