I ordered 6 from Ideal last Fall. I ended up with 3 pairs. All lived happy and healthy. IMHO, I think it depends on who/where you get them from. Like someone else suggested, the author could have gotten their birds with "bad" genetics. It is also true that they are susceptible to Mareks, especially when young. No idea why this is. The fact that they are a small breed is also a possibility as they may be too small to get out of the egg. A note on the fertility: The reason the author of the book says they have poor fertility is because of the rose comb combined with the hen-feathering. Both traits can inhibit fertility in birds which is often why you can receive single combed individuals from hatcheries as they go for quantity rather than quality. Same thing with the hen-feathering. They may use roosters that do not show hen-feathering as they will produce more.
Though, as several of you have shown from your own experiences, not all of these are 100% true, but they can happen.
For those asking about the Silver x Golden crosses:
Golden cock x Silver hen = Golden pullets
Silver cock x Golden hen = Silver pullets
Cockerels from both crosses will be a mix of gold and silver (more like a yellow-ish or silver leaking gold, etc. etc., you get the idea).