I have had my Gerbing jacket, pants and gloves for a couple winters now, and have found the following set up to work best for me. I commute to DC 110 miles a day roundtrip, regardless of the temperature or weather (unless it's snowing or my driveway is iced over, I'm riding).
When it's really cold out (teens) my first layer is a long sleeve compression shirt from Cabelas for insulation and to keep any perspiriation moving away from me. Second layer is the gerbing jacket, third layer is a Cabelas TEF 60 Windshear jacket.
http://www.cabelas.com/mens-uninsulated-outerwear-cabelas-t-e-f-60-windshear-8482-jacket-150-tall-1.shtml
The windshear jacket absolutely does not let air in, and is the best fleece I have ever owned for staying totally warm. I have probably 20+ different fleece jackets, pullovers, etc. that I have bought over the years trying to find the right one for really cold weather riding, and this did the trick. The collar on the windshear jacket works perfectly as a neck liner for my Darien riding jacket. I wish riding gloves were made of this magic material!!!
I have a dual controller for my gerbing gear, but have found that my hands get cold when I have the jacket set at the right temperature, or the jacket gets too hot when my hands are comfortable. It all depends on air-flow. On my ST1300, and prior fully faired bikes, I didn't need anything but heated gloves until temps dropped to the single digits. I only bought the heated gear when I had to get through my first winter on the 800 GS. When it's really cold, I use the separate wire harness for the gloves without plugging them into the jacket (this way they are independent of the controller). This allows me to have the pants and jacket running at a comfortable setting, and the gloves default to running at full blast. (Which is still not enough sometimes.)
I also have a very thin, totally windproof balaclava that I wear under my helmet. The balaclava is made by Schoompa? (not positive) and makes the seal between jacket and helmet complete. It also helps tremendously with keeping my throat from freezing. My one complaint about the balaclava is that it makes the helmet a bit snugger than I would like.
When it's a bit warmer, (mid-30s and up), I prefer to use a neck warmer I found in the clearance section of a BMW shop - this is basically it:
http://www.sierrabmwonline.com/product_info.php/bmw-neck-warmer-2011-cold-weather-gear-76238520-885-887-p-985 No claustrophobia in the helmet, and a reasonably toasty neck with no drafts.
We have tremendously humid summers here, and riding in heavy traffic in the afternoon can be a toasty experience when temps are in the 90's with 100+ humidity, bright sunshine, hot asphalt, and no airflow.
For these kinds of commutes, I wear a cotton long sleeved t-shirt that I wet down a bit before walking out of the office, and have all the vents on the Darien jacket open. It helps, but I feel like I still lose about 5 pounds on my way home!
I always wear jeans under my Darien pants for commuting, and just accept the fact that I will be warm.
For longer rides in this kind of weather, I have a hydration pack, and I often fill the front pockets of the Darien with ice from the drink vending machines at the gas station or truck stop. Instead of the jeans, I wear some seamless long wicking underpants I picked up on sale at a BMW shop - (not exactly these, but basically the same thing)
http://www.ascycles.com/detail.aspx?ID=76252
I also wear a shirt of the same material, which breathes better than the cotton long sleeved t-shirt. A disadvantage of the BMW underpants is that more or less nothing is left to the imagination when you take your riding pants off... in the interest of modesty and not scaring the general public, I slip my jeans over them when I know I'll be stopped for a bit and don't want to wear the riding pants.
Chris