I haven't handled a 903, but I do really like the 940. As for the comparisons:
S30V vs. 154CM - both are excellent steels and would work more than adequately for the uses you listed. S30V generally has better wear resistance than 154CM.
Aluminum vs. G10 -this is more a matter of preference. The G10 on the 903 looks like it's textured, so it may offer better traction. Textured G10 will also wear out your pockets faster. Personally, I haven't found the aluminum on the 940 to be slippery, even when I'm sweating profusely in our 100+ degree summer days.
3.4" vs. 2.95" blade - this can also be a matter of preference. Length restrictions can vary by location. The 940 is a deceptively compact knife for having a 3.4" blade though. The Mini-Grip has a 2.9" blade, and I haven't ever found that length lacking for my EDC uses either.