C: I was pleasantly surprised regarding the users interface. After reading all the criticisms here, and using firmware 1.20, I'm really having no problems. And I'm finding it easy to learn and easy to use. There is a lot of redundancy among the keys to accomplish actually just the few functions that the player performs. The one thing I haven't figured out is the shortcuts that you can bring up when a song is playing, and how to favorite that song while it is playing. But I haven't tried really.
D: I assumed that I could transfer song files to the micro SD cards quicker if I put them in my computer directly. Based on the manual, it seems like this is not true. It seems like the write speed is the same regardless of whether you connect your X5 to your computer as a storage device, or remove the card and put it directly in your computer. In any case, when you use your computer, you are only dealing with one card at a time.
Formatting however, was quite easy if you let the X5 do the formatting for you. I just inserted my cards and went to the format menu and then selected "format" and it was done in seconds. However, the X5 named the cards according to the slot they are in. And I wonder what would happen if I formatted multiple cards in the same slot for future swapping out. Would they have the same names? If two cards with the same names are inserted in the X5, would that confuse the X5 at all when you are browsing by files?