Answer:
It is possible to setup a BER measurement for the 4-PAM link by using the BER Test Set component. The test set creates a binary bit stream and compares this stream with the received bit stream after the PAM sequence has been decoded and converted to a binary data signal format.
As expected, the BER performance of the link is very sensitive to the threshold amplitude settings within the M-ary Threshold Detector component. Also, if the bit rate is changed I recommend that you take a look at the Binary Sequence Visualizer and the Binary Sequence Visualizer 1. At 5 Gb/s, I noticed a delay between the 2 streams (about 0.25 ns), which I was able to correct by adding a delay compensation within the Data Recovery component.
I have enclosed a network design that has been setup for a 5 Gb/s link.