I own a 24-70L Classic. I've rented it several times. I own a 24-105. Roger@LensRentals has shown that the plastic sleeves on the "pins" that handle the zooming tend to wear out worse than any other lens, so with heavy use they can get inconsistent; supposedly the Mark II is vastly improved in this department. That said, my 24-70 is excellent, outperforms my 24-105 by a mile (just feel like everything shot with the 24-105 is "flat", while the 24-70 has sizzle). When I got the 24-70, my wife got the 24-105; I don't miss it, and I'm fearful of the day when she asks for a 24-70 of her own. If money were no object, I suspect the 24-70 would be the only zoom lens I'd own - I'm the kind of person who will take bodies and primes regardless of weight, and the 24-70 is good enough that I feel like I could skip a few primes in that range and not regret it. (For our last Alaska cruise in August, the 40D/10-22 got relegated to time lapse duties, while we spent the week with 1D3+14/2.8, 7D+24-70, 7D+70-200/4IS, 1DX+400DO+1.4xTCIII, and the 16-35/2.8II never got used, while our 24-105 and 70-200/2.8 stayed at home.)