We've done the drive in winter weather 2 round-trips, so twice down, twice back...3 of 4 were fine, great even. The fourth (coming home in Dec I believe--if not, it was coming home in Feb.)--white-knuckling it. It was snowing, and they reduced the speed on the "fast" road to Houlton (sorry, I haven't commited the hwy #s to memory!), down to 50 or 60 kms per hour, so we decided, huh, might as well take the airline if we can't go at 120 kms. It was AWFUL. The road was bad, not well-plowed, slow, dark, windy. (That's WIIIIndy, winding, not windy, as in lots of wind!) Thank God there was little traffic. (Though if we'd had a problem, no-one would've been handy to help!) That said, the interstate was a real disappointment too. The snow wasn't THAT bad, and here, well, we'd just clear it. It seemed like all that we-hate-to-pay-taxes stuff meant they weren't prepared to spend money on snowclearing, and the interstate, through NH up into ME where we branched off toward Calais, was in bad shape.
Our strategy this time is to go into it knowing we'll just STOP and take a hotel if we need to. We'll watch the weather and leave early if it's threatening, and we're coming back a day or two before we have to on the way home, so we can take our time getting home if need be.
I'd be curious to hear if others have travelled the interstate through Maine in heavy snow. Because if the state of snowclearing we saw was normal, then I'd say in bad weather neither route is good.