I don't think the crest has anything to do with being caught by a hawk. I raised crested bantams for many years free range and they never had any more problems with being caught by hawks or other predators than my non crested chickens. Chickens turn their heads to the side when they look up at the sky. I think for our Swedish flower hens to have a crest as large as the show type polish chickens is not going to happen unless the genes for extremely large show type crests are already in the Swedish flower hen. I haven't seen any with crests that large posted to the list yet. I actually haven't seen a crest large enough to impede the chickens vision posted yet. That doesn't mean there aren't any like that being raised just that none have been posted in my opinion. I bred the crested bantams for over 10 years crested to crested and never had a problem with them as far as health and the crests never became as large as the show type polish breed.
Well, it's the only bird, out of over 100, that I have lost to a hawk. It did make me wonder. Her crest was quite large and very poofy. She was cute, but I had tagged her to be careful breeding.
I wouldn't do crested on crested because of the vaulted skulls resulting in decreased hatchability, plus the large crest isn't what we think of when we think SFH.