4GB read/write speed slower than 2GB?

I heard some rumors about it.Is it true?

*Shrug*
I had a 1gb standard blue sandisk card, now a 4gb sandisk Ultra II.

Seem about the same speed, I don't think the PSP can make use of the Ultra II range's extra speed.

Writing many small files is always going to be slower than 1 large file of equal total size, regardless of what type of mstick.

Basically as long as you get an official card you really shouldn't have any problem with speeds.
Those MAX HDD addons are supposed to be considerably slower though.

If they are slower, it's not enough to make any real difference except possibly when connected via USB. Except, as mentioned, for the Datel HD, which I've heard has performance problems when watching videos amongst other things.