One of the major difference is the body diameter,
It's an important ergonomic factor that haven't been mention in this thread.
I find most 3x18650 type of HID body being too fat to hold comfortably, The magic Fire has 4x18650, thus even fatter.
I think people with smaller hands may soon realize how uncomfortable it may get after holding it for a while.
SSK-33 is very slim for 3x18650 arrangement. They come in stock at 6x28650,
I had to cut it down to 3x18650. Lots of work, but in the end, it's both shorter & slimmer than magic fire.
I find it much more important to have a slim body than extra 5 watts, that's why I have 3x18650 35W Firefox I, but was never interested in the 4x18650 40W version of Firefox II.