I think it might have something to do with read/write speeds. My Class 4 has roughly the same read/write speed, whereas the Class 6 had a significantly slower write than it had read. But I'm just guessing.
As for response time.....the class 6 is 0.8ms and the Class 4 is 1.6ms. Yet the ONLY game the Class 4 has an issue with is Castlevania PoR. wacko.gif But then again, I have by no means played all the DS ROMs.
I know one of the people that told me they had the same issue said the card worked just fine in their DSTT or EDGE (can't rem which it was), so it's definitely an issue with the Cyclo just being particular.
I wrote up a post at the TC forums (when they were still up) saying about the same thing I said in my previous reply and have never received any kind of response from TC directly about it, other than to try this-or-that from other members, which I had already done. TC themselves never actually responded. One thing someone there noticed is that cards that didn't work right formatted to a different size than the same brand that DID work right, which is why I asked about format size in my previous reply.
I have heard people complain about A-Data doing the same thing to them on Cyclo's, but I don't have any A-Data cards to test that.
OH, and I forgot one little tidbit of the flakiness I mentioned.....the Class 6 wouldn't allow a firmware update of the Cyclo to complete. huh.gif
It's all pretty annoying to me because I bought that Class 6 FOR the CycloDS so I wouldn't have issues with any games. Boy did that backfire. blush.gif