I realize this is a very old thread, but with all of the new flash devices and clones on the market I wanted to comment on the Super UFO. I don't think it is a very good flash device, but it is useful for diagnostic purposes.
It is useful for game saves, region bypass, ROM dumping, and diagnostic capabilities of the cart, but it is NOT the best option to play ROMS. There is a utility on the SUPER UFO that will "read" the console and tell you which revision of the hardware you have internally. It is a little bit buried in the menus, but this function is there.
This is useful because many S-CPU chips had DMA/HDMA defect and to a lesser extent, many S-PPU2 chips had problems. This is why they were quickly revised for the North American launch in 1991.
CPU Version
(1) S-CPU--often defective-- (2) S-CPU A (3) S-CPU B, etc
PPU1 Version
(1) S-PPU1 (2) S-PPU1 A (3) S-PPU1 B, etc
PPU2 Version
(1) S-PPU2--sometimes defective--(2) S-PPU 2 A (3) S-PPU 2 B, etc
So, it is nice to pop the cart in, run the check and save yourself from wasting time replacing caps on a board with a failing S-CPU or S-PPU2 from 1990.
That being said, as a flash device for real Super Nintendo consoles, it is not very good.
First, even for a flash device it is way off spec. It is a 3.3 volt device running on a 5 volt slot with inadequate means to address that difference. Second, the SNES had many revisions of the CPU, PPU1, PPU2, and the CIC chip. Certain combinations of these chips will cause the Super UFO not to work or to randomly work on some games, but not others.
I have noticed that consoles with the earliest revision of the CPU and possibly the earliest revision of PPU2 sometimes have problems with the Super UFO. However, clones like the FC Twin usually have no problems with it.
Third, as the Super UFO is based on the legacy technology of game copiers that were sold when the SNES was still in stores, one would expect elements of late SNES revisions that interfered with those devices to also interfere with the Super UFO. I've personally experienced this with games like Demon's Crest (I actually had to find an old hacked version to get past a certain point in the game where the CIC would kick in and block your progress).
Finally, the battery system on these cartridges is abysmal, with games sometimes being corrupted within the DRAM as you play them.
In my opinion, none of this is worth paying more than $25. The Super Ever Drive and SD2NES are on a completely different level than this thing.