No other cart except the Acekard has true 100% compatibility with no bugs/slowdowns. And rarely does any cart support download play properly.
The Acekard scored 7.5 with its 100% compatibility, the reason it scored 1 point lower than the UFPEX is because it requires you to format your micro SD card with a proprietary file system severely crippling ease of use for your micro SD card. The Acekard software also inhibited other bugs and problems that randomly formatted the cart.
The UFPEX boasts 100% compatibility, FAT32 support, nice(ish) GUI, drag and drop (though somewhat slow), DLDI support and a cheap price tag. It does its job perfectly. But certain problems just prevent it from being on par with other slot 1 solutions such as the R4.
I think for what the UFPEX offers; it deserves the 8.5 score.