100% compatibility, supports clean ROMS, works on NDS, NDSL, NDSi and NDS XL.
Golden Sun: Dark Dawn (U): Black screen, didn’t even work in special mode. Call of Duty: Black Ops (E): Black screen, didn’t work in special mode. Toy Story 3 (E): White screen, didn’t work in secial mode.
Wow 100% compatibility sure means something different now.
The special mode works only with a fast MicroSD card.
What are you actually basing that on? Why not use the MicroSD card you use with your Supercard DSTWO? I am assuming it would work fine if it were the MicroSD card that's the problem.
A non-spring-loaded slot is something I see as a positive thing. My non-spring-loaded Edge and R4 are great and easy to handle, my spring-loaded Acekard sucks ass (good thing one can use it without the springy-thingy as well).
Your Sandisk card should be fast enough, I would guess. I've never had any speed issues with genuine Sandisk cards, no matter what generation - they constantly perform faster than the competitors, as far as I tested them. (I got ~5 Sandisk cards, 1 Kingston, 1 Transcend, 1 No-name - the Sandisks are the fastest of their respective generations).
I like the spring loaded cards more because you can just click the MicroSD out with your fingernail (if they aren't too shot).