Can't compare for you, but it sounds like the Gamma MX would be your best bet for winter riding, as it's got more of the warmth and wind-resistance, but still breathes well. When the temps get above about 40, I've ridden with my MX and just a shirt underneath.

Thanks for the help! Would opening the chest pockets in the MX provide venting like pit zips?

I would recommend the Gamma LT if you are wearing a fleece underneath and doing an activity like bike riding if the temp will only be 30-40 degrees... I would get too hot in the gamma mx I think but I dont own it!