Well I'm not going to opine or state facts either way and I won't praise or discredit A. E. Haas, but here's a little reasoning that may help:
If the goal is to achieve the manufacturer-designed viscosity at full operating temperature as soon as possible, then it seems to make sense that "there is no such thing as too thin at startup" oil unless you're starting the car while the oil is at 415 degrees F and it's thinner than spec'd at operating temperature, but you live in Georgia, not on Mercury, so I don't think that's a problem. And you drive 3 miles to work that might not get the oil up to full temp.
OK, so 3 miles each way 5 days a week is 30 miles per week of commuting. If you drive more than 30 miles on the weekends and the oil gets up to full temp, then it seems like an xW-30 would result in driving the car with oil that's thinner than the spec for longer than an xW-40 would result in driving with oil that's thicker than spec. Make sense? Assuming you drive 30 miles or more on the weekends and the oil gets up to full temp for that time, then I would split the difference and use a 0W-40 oil. That will get you the closest to spec'd oil viscosity for the short trip weekday driving and at you'll be at the spec'd viscosity on the weekends which is where more miles accumulate anyway.
Either way, whether you go with an xW-30 or an xW-40, I'd use a 0W oil to get the maximum possible oil flow while the engine is not at full operating temperature. If it was me, and my goal was to achieve the best possibility of low wear numbers, I think I'd use a synthetic 0W-40 like Mobil 1, as has already been suggested, because it is possible the oil gets up to full operating temperature by the time you get to the bus stop and why risk having something in there that's thinner than the designers intended? Whichever brand 0W-40 you feel generates the lowest wear numbers would be the right choice for your own peace of mind.
The big question in my mind is why do the manufacturers suggest a 15W-40 over a 0W-40? Is there something about oil pumps or engine design that makes a 15W-40 a better choice than a 0W-40, other than "the manufacturer said so?" I'm hoping for a sound technical explanation. The theories presented by A. E. Haas make sense to me, but I'm open to all facts at all times to make the best possible decisions.
Cheers!
John