Keeping my torso and legs warm is the easy part. I have a pair of Tourmaster jackets. My Flex III waist jacket covers a wide temperature range. As the temperature hits 50 and even toward 40, I wear a sweatshirt and/or fleece (or hoodie) under it. I also have a Tourmaster Saber coat length winter jacket. I've simply never been cold underneath it, and with panels zipped open, it can get me through moderate (up to mid 70s) afternoons without overheating.
For my legs, I zip the panels onto my Tourmaster pants. Rather than mess with bulky pant liners on cold days, I'll either wear long undies under my jeans, or pull my Coleman waterproof ducks over my Tourmasters.
Like others said, keeping the extremities warm is the harder part, and I've never quite mastered it. Full disclosure - I don't have heated gear, and that would certainly help. What goes a long way for me is wearing glove and sock liners under good gloves and wool blend socks. Watch for Cycle Gear's periodic sales; they're a good source of glove & sock liners, balaclavas, and long undergarments, and they're quite cheap when being sold as loss leaders. You mentioned gauntlet style gloves, and I prefer them to gloves that cinch around my wrists - but that's purely a personal preference.
One thing you just have to deal with is this: very few riders find a one-size-fits-all solution. Most of us end up with an assortment of jackets, pants, and gloves, plus a collection of layers, that we've worked out through trial and error.
As for the Boulder II jacket, you'll have to find out if it works for you. I've never looked at one in person, certainly never worn one. I did look at some online reviews, and they were less than enthusiastic about it in cold or wet weather.
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