The M3 Lite Perfect (ignore the 'Pro' version) is a slot-2 based M3, it has greater advantages over slot-1 devices, however has the downsides of higher price and more complexity. The M3 Lite can be used for NDS and GBA games, it also has 32MB of SRAM which can be used in conjunction with a patched NDS Browser ROM and slot-1 device for internet access. Generally if someone had bought both the Simply and Lite they are looking to use the Simply for NDS games and running the NDS browser, and the Simply for everything else (homebrew, RAM, GBA games, Media)
basically, the patch allows the backup [ran fom slot-1] to access the m3 lite perfect [NOT pro]'s 32MB of ram as the ram expansion pack. the slot-1 device [doesn't have to be m3dss] emulates the real browser cartridge while the m3 lite [supercard/sc lite(non-rumble), also works] emulates the real ram expansion. that's why you need BOTH devices for this to work. i use the simply for backups/homebrew and the m3 lite for media/older homebrew/gba/cheats via dipstar/trying to dump games[and failing]/ram expansion pak.../other.
