For what it's worth, I've been in Maine (as well as Washington State) in the winter (in Presque Isle, ME, Madawaska, ME, and Bremerton, WA; heck, I got accepted to and almost attended UofME at Orono) and have never had any issues with any battery I've had installed at the time other than just standard failure due to age and what not. To include Die Hard, Interstate, Optima Red tops, and Optima Yellow tops. While I understand the concern for CCA and wanting the reliability of the battery in the cold season (which we all know is quite long in Maine), your counter-argument about weight savings of 2lbs, battery appearance, or what not are just B.S. excuses. I would worry less about a 2lbs savings or addition if it meant that I could depend on the battery; your handling for a 2lb difference is negligible and unless you're driving at the limit everywhere you go (getting speeding tickets for frayed/broken throttle cables weekly), you're not going to notice this. So, stop wasting everyone's time with excuses. You choices are, reliability, cost, or quality, pick two and call it a day.
And, I've had both good and bad experiences with Optima batteries; just like any other battery, they have had quality issues. The thing I love about Optima batteries is they are maintenance free without having to worry about electrolyte depletion (like a typical liquid lead-acid battery) and they don't acid up the electrodes much at all (if you've every had a Die Hard, you'll know the pain). Do Wal-Mart batteries have these issues? I'm not sure, I don't buy anything from Wal-Mart unless I have to as I don't like them as a corporation; but if you're happy with them, last you the length of time you deem to be enough to be satisfied with your purchase, and start the car in the dead of winter when you need it to, then it sounds like it is what you want.