Fan spinner cones shapes - An interesting subject...
Not only does the shape have an impact on shedding ice, the shape plays an important role in water ingestion. There was an early B-737-300 incident with CFM56-3 engines where this was learned. TACA Flt. 110 was beginning decent into New Orleans and passed through some heave rain. Both engines flamed-out and the aircraft landed without power on a levee near the NASA facility. This aircraft had "Madonna" spinner cones on the engines. These spinner cones evolved from the original CFM56-2 which had long, large & pointy cones.
What was determined was the FAA test for water ingestion, during the CFM56-3 engine certification process, did not call for enough water and did not duplicate what was encountered in this rain incident. So, the spinner cone was changed from the "Madonna", to the "Dolly". It isn't that pointy cones don't work, they do but it depends on other factors as to how well they work.
Personally, I like the "Dolly" size and shape the best!
The stripes painted on the cones are primarily for ground crews, the bird theory is still a theory. The paint stripes can also tell which way the engine fan is turning. The fan can be windmilling in the opposite direction of normal rotation depending on wind direction. I am not sure, but, this could have a negative effect on starter life?