>>>If you transfer between them. On the same cable it will suck. <<<
T'aint necessarily so. I have had dual hard drives on the same cable for probably 6 years now in two different computers, and have never had a problem of that nature. As long as one is Master and the other Slave, it works. I use the Cable Select jumper setting and use CSEL cable, and the cable position then decides which is M or S. (End is M and middle is S)