Think that Huma may well use cheaper materials/builders anyway - to maximise their profits, and to offset the delays so far.
I spoke to Pilar at Huma yesterday, and yes compensation is to be awarded - she said it will depend on the individual - waiting time, amount invested etc. She also said that deposits would be refunded if people choose to pull out, whereas back in May, she told me the complete opposite! Either Huma's legal team have put them straight on their obligations, or the right hand doesn't know what the left hand is doing...
I think whatever we do, we need to act as a cohesive group as much as possible - if people do decide to take legal action, then we should all use the same lawyer - much more intimidating than people acting in dribs and drabs over a period of time.
A Spanish judge would also be naturally more disposed to sit up and take notice of a group action, IMHO.