yes, there is only a 25% chance of having a homozygous crested offspring, that may or may not have a vaulted skull. and those vaulted skull chicks may or may not have problems down the road, same as the huge crests, but why take that chance?
personally, I will NOT breed crest to crest. for each crest to no-crest breeding you still get a 50/50 chance of getting crested chicks. the other 50% will be uncrested and unaffected by any associated (potential) problems.
just my 2c.
glad to hear you had a successful hatch ancientoaks.