The E Loads aren't an option for me because 98% of the time my truck is running it's just me in it. I ran the KO2 E loads for 21kmi before ditching them, the horrible ride was just one of the problems I had with those.
The lack of snow traction was one of the biggest complaints from the AT2 that was supposed to be improved in the AT3. I've been trying to read up more on it, but apparently each manufacturer keeps the actual silica / silane mixtures a closely guarded secret. There's got to be more than a slight difference in compound between the P & LT tires with a 15k mi difference in the warranty. I am left wondering if that would be enough to cause noticeable difference in cold weather/snow/ice grip.
Now that I'm thinking more about weight, I've also wonder if you're running a tire designed for X weight on it, and you've only got 60% of X that the tire will not provide as much grip as designed because it's not being deformed enough by the weight put on it. Sure the sidewall will flex more with a lower psi, but if the actual tread isn't deformed as designed that's got to impact grip/traction too. Maybe an unrealized drawback of going to E load?

While my front are Icon LT, the rear is just stock. I doubt I'd be able to run those without reconfiguring more of the suspension than I'd like to get into.