I think it all comes down to what material feels best to the individual ... attempting to apply logic to something that's more a matter of feel, and perhaps also appearance, might become an exercise in futility.
I'm afraid that I must not be very perceptive in regards to this subject, as I seem to be happy with a wide range of grip materials. In terms of what's currently on my 1911s, it's both G10 and wood.
With respect to very hard materials, such as G10, they can do some damage to a nice blued finish. Grip screws are also more likely to work themselves loose over the course of firing 100s of rounds. But there are easy solutions for these issues, so I don't view this matter as being a real problem... as long as one is aware and attentive. Otherwise G10, strictly as a material, has some nice properties in regard to durability, resistance to expansion, and resistance to elements than can damage some other grips. But since grips are mostly rather inexpensive, I don't think durability should be viewed as important as feel to most shooters ... I.e., use what you like.
Alumagrips.com grips (fabricated from precision machined aluminum is another interesting alternative)