K, so here's what I have personally tested using my r4 and a 1gb Kingston MicroSD (Japan).
AAAHH!!! Real Monsters // Unplayable, flashing layers.
Aladdin // Unplayable, does not go past welcome screen.
Battletoads & Double Dragon // Unplayable, froze the DS when loading ROM.
Beavis and Butt-Head // Playable, %100 everything. Set layers to 3/3/3/3 and turn on Wait vblank.
Bikermice from Mars // Unplayable, froze after loading past the difficulty options.
Boogerman - A Pick and Flick Adventure // Nothing happens when ROM is loaded.
California Games II // Unlayable, Sound is a bit laggy/sluggish, not all layers are rendered properly.
Castlevania - Dracula X // Game works, but it's very slow even with full speed hack. Some Flashing layers.
Castlevania - Vampire's Kiss // Game doesn't go past New Game selectin.
Clay Fighter // Nothing happens when ROM is loaded. Second time loading it froze the DS.
Clay Fighter 2 - Judgment Clay // Game loads, but once you enter a fight lots of flashing layers and
SNEsmulDS is unresponsive.
Contra III - The Alien Wars // Almost playable! When background has animation everything is slowed down.
Some objects are invisible such as the tank in the first level. Set Layers to auto, no vblank and full
speed hacks.
Cool Spot // Unplayable, background is static, nothing moves and there is a black bar scrolling vertically.
Donkey Kong Country 2 - Diddy's Kong Quest // Unplayable, randomly freezes after time and flashing layers.
Donkey Kong Country 3 - Dixie Kong's Double Trouble // Unplayable - flashing layers.
Donkey Kong Country // Unplayable - flashing layers.
Doom // Nothing happens when ROM is loaded.
Double Dragon V - The Shadow Falls // Freezes when entering the game.
Earthbound // Playable, sometimes items and characters show up through the overlay HUD.
Earthworm Jim // %100 Playable, use 1/1/1/1 layers.
Fatal Fury // Unplayable, missing layers.
Fatal Fury 2 // Unplayable, missing layers.
Final Fight // Unplayble, loads to a white screen.
Final Fight 2 // Nothing happens when ROM is loaded.
Final Fight 3 // Nothing happens when ROM is loaded.
Final Fight Guy // Nothing happens when ROM is loaded.
Final Fantasy - Mystic Quest // Unplayable, doesn't load anything past the splash screen.
Final Fantasy II // Unplayable, blue speech/action bubbles do not contain text.
Final Fantasy III // Unplayable, sound is squeeky & loud with flashing layers.
F-ZERO // Unplayable, doesn't render layers correctly, sound skips.
Harvest Moon // Unplayable, layers aren't being rendered correctly.
Home Alone // Unplayable, flashing layers.
Home Alone 2 - Lost in New York // Very playable, the game sucks though.
Killer Instinct (?) // Large LoROM not Supported and freezes the DS when loading the ROM.
Killer Instinct (E) // Unplayable, layers aren't rendered correctly.
Killer Instinct (U) (V1.0) // Unplayable, layers aren't rendered correctly.
Killer Instinct (U) (V1.1) // Unplayable, layers aren't rendered correctly.
Krusty's Super Fun House // Unplayable, layers aren't rendered correctly.
Legend of Zelda, The - A Link to the Past // Quite playable, sound and game runs a bit fast though despite
what speed hack setting you use.
Mega Man VII // Doesn't load past the Capcom logo.
Mega Man X // Playable, but audio and game runs fast despite speed hack settings.
Mega Man X 2 // Unplayable, missing layers, also corrupts the SNEmulDS menu until you restart the DS.
Mega Man X 3 // Unplayable missing layers.
Mortal Kombat // Unplayable, flashing/missing layers.
Mortal Kombat II // Does not load past the yellow intro text.
Mortal Kombat 3 // Does not load past the intro logos.
Pac-Man 2 - The New Adventures // Freezes at Pac-Man2 logo.
Paperboy 2 // Somewhat playable, flashing layer on the left side. Audio is really loud for some reason too.
Primal Rage (E) // Doesn't do anything when ROM is loaded.
Primal Rage (U) // Doesn't do anything when ROM is loaded.
Rock N' Roll Racing // Doesn't do anything when ROM is loaded.
Simpsons, The - Bart's Nightmare // Layers aren't rendered correctly.
Street Fighter Alpha 2 // Large LoROM not Supported and freezes the DS when loading the ROM.
Street Fighter II Turbo // Unplayable, doesn't display anything when you are in a match and judging by the
sound, it's running at ultra speed despite which speed hack you choose.
Super Bomberman // Freezes after selecting Normal Game.
Super Bomberman 2 // Game map does not move, no sense of direction.
Super Castlevania IV // Flashing layers in the first area, once inside it seems ok if you tweak speed hack
settings and vblank.
Super Double Dragon // Nothing happens when the ROM is loaded.
Super Mario All-Stars // Freezes the DS when you select a game.
Super Mario Kart (U) // Does not load past the Nintendo logo.
Super Mario Kart (E) // Does not load past the Nintendo logo.
Super Mario RPG - Legend of the Seven Stars // Large LoROM not Supported and freezes the DS when loading the
ROM.
Super Mario World 2 - Yoshi's Island // Nothing happens when the ROM is loaded and corrupts the SNEmulDS
menu until you restart the Ds.
Super Mario World // Very playable, almost %100!
Super Metroid (JU) // Playable!
Super Street Fighter II - The New Challengers // Loads nicely but input isn't recognized and then freezes.
Test Drive II - The Duel // Doesn't render properly at all.
Toy Story // Doesn't render properly at all and corrupts the SNEmulDS menu until you restart the DS.
Ultima - Runes of Virtue II // No sound, very laggy despite the speedhack settings used/
Ultima VI - The False Prophet // Seems playable, I didn't get very far though, someone may want to test it
further.
Ultima VII - The Black Gate // Seems playable, I didn't get very far though, someone may want to test it
further.
Ultimate Mortal Kombat 3 // Does not load past the intro text.
Xardion // Seems very playable, never played the game before though.
So after all of that, I really only recommend Earthworm Jim, Earthbound, Beavis & Butthead and Super Mario World, Super Metroid for this beta