After doing more reading
, the theoretical EDGE max is 384k which is using 8 slots in the same direction (48kX8). As joginder said, the highest class device is class 10 which only utilizes 5 active slots.
@Zoinks, you would change your slots to fit your needs. If you were uploading heavily you may want to use 3+2 which would give you two upload slots or 96k up. Most people would probably use 4+1 to max the download. It's just another setting to tweak???