Assuming the mechanism is reading the data off the CD with reasonable accuracy (i.e., not enough errors to overwhelm the error-correction function), there is no physical mechanism by which transports could sound different. As Kjg says, if they do, one of them is broken.
As for "jitter signatures," there is no jitter in a transport. None. Jitter only occurs at a conversion point, which means it happens in the DAC. Any decently designed DAC (and in the high end, you can't assume anything) will reclock the incoming bit stream, so timing errors in the transport are irrelevant.
As for "jitter signatures," there is no jitter in a transport. None. Jitter only occurs at a conversion point, which means it happens in the DAC. Any decently designed DAC (and in the high end, you can't assume anything) will reclock the incoming bit stream, so timing errors in the transport are irrelevant.