"New genetic material is not necessary."
Really? Then how do you get from Bacteria to Blue Whales? Through a loss of information?
Re: Sickle Cell
The symptoms of this "good" mutation include: acute attacks of abdominal and joint pain, ulcers on the legs, defective red blood cells, and severe anemia -- often leading to death.
You're talking about full-blown SSA, where a person inherits two SSA alleles. SSA is recessive- if you receive only one allele, the effects are positive.