I just bought a ND2901 and found that the average copy speed of my 2 SD cards is about 15 MB/s which is much lower than the advertised 40 MB/s.
The first card is a Sandisk Extreme Pro 95 MB/s SDXC, and the second one is a Sandisk Extreme 60 MB/s SDCX. I tested both cards can read at their rated speed when using a Macbook Air.
The strange part is that when I copy the 2 SD cards using a SD-to-CF converter, the speed is raised to 25 MB/s. The converter specification states 25 MB/s is the fastest speed it can do, so the bottleneck is on the converter and not the card. But it is still much faster than using the plain SD card.
I am wondering if my ND2901 is faulty or not. Can someone please give me some advice? Thanks.