Honestly, unless you are using really big files you will probably not notice the difference. Most files on smartphones are tiny by PC standards (a few megs at most). You would probably only see a difference if you benchmarked it.
Pictures will be a meg or so, and video will stream. You might notice it with some of the bigger games, but I doubt it even then.
That being said, I tend to store all my media on external memory and installed programs internally...that way if the phone breaks or I need to transfer without using the phone I can just yank out the SD card, stick it in an SD reader, and transfer it that way. If my phone breaks I can just transfer the SD card to the new phone and all my media with it. And media files are completely independent of any installed programs, so no need to worry about breaking anything with the transfer.