Took this from Synthtopia.com.
"One limitation of 606 sequencing worth noting is that you can't play back a sample at different pitches. Many samplers make it easy to play a sample at different pitches, so it's surprising to see this absent. Our contact with Roland says this is because the SP-606 is designed to be a phrase sampler, and doesn't do keyfollow of samples. The expectation is that you will sample entire phrases, instead of building musical lines from pitch-shifted samples.
If you prefer, you can resample pitch-shifted samples and save them to new locations, but this means means that playing a simple bass line with the SP-606 will eat up a lot of pad locations. Keep in mind the 606's generous sample capacity, though, and it's easy to find workarounds for this."
I would consider this a pretty huge oversite by Roland.
What a terribly failed attempt at competing with the mpc1000.
If your interested in an Roland/boss sp, and want to pitch your samples for easier bassline/melody creation then look at the sp505 instead.