Warm in winter-foam survival clothing!

One thing that has constantly worried me about my prep efforts is keeping warm in the winter.  I am one of those people who are always cold!  I sometimes start shivering on my way to the bathroom in the middle of the night!  My home doesn't have a fireplace...I've thought of putting one in, but you also have to store enough wood.  Propane heaters are great for a few days.  But I've always wanted something for if I had to go longer without heat.  I know some people in the US were without power for weeks last winter...and that was just for a localized natural disaster.
So I decided to look into these foam winter survival suits designed by Jim Phillips.  His clothing has been used in the Iditarod, North Pole expeditions & by the military.  The foam is very breathable...you don't wear anything water proof over it.  Your body heat alone will dry it out & keep you warm.  You can buy the materials to make a full suit for around $100.  Now that sounds pricey...but start adding up the cost of your snow pants, coat, shell, hat, gloves, etc.  Or compare to the cost of putting in a fireplace, or a year worth of propane.  As an added bonus, you can use these anywhere.  If you have to evacuate, or even live outside, you could still use these.  To me that's a big plus.
Now my understanding is you have to have a stronger sewing machine to sew on the foam.  Additionally, I don't know how to sew.  So I paid someone to make the suit for me.  Stylish it is not.  But is it warm?
The first time I tested it, I wore it to an outing my son had outside.  It was sunny & about 37 degrees.  Soon I was HOT.  Good sign for someone who's always cold!  Next I tested it outside in the dark when it was about 21 degrees.  I could tell it was a lot warmer than my regular winter gear.  I stayed comfortable & toasty!  And that's saying a lot considering how cold I usually am!  They are also a lot more comfortable than I feared.  I was picturing a wet suit like feel.  But it's quite flexible & not uncomfy.  You can also wear clothing over the top (although not something waterproof, that stops the "breathing" capability).  This would be an especially good idea if you were evacuating so others wouldn't know you had the clothes & want to steal them.
I am now having an outfit made for my son.  With him we are making the arms & legs longer, & making it just a bit bigger around than he is.  I'm hoping in this way to have it "fit" for a few years.  Then I will pass it on to younger cousins.  I will probably keep some foam & a pattern on hand as well.  Worse case we could sew one by hand if necessary.  Then I'll have to make him a new one every few years.
Ok, this still wouldn't be my first choice for a whole winter!  I don't WANT to have a winter without heat!  But so far this is the most versatile heating method I've found.  It would help in almost any situation, & it's actually affordable.
Any search online for "foam winter clothing" or "Jim Phillps" will help you find more information.  Many people do group buys on the foam to get a better price.  Here's a few websites with info to get started:
http://www.jimsway.com/atjs1.html
http://www.motherearthnews.com/Do-It-Yourself/1985-01-01/Make-Your-Own-Cold-Weather-Clothing.aspx
http://squattheplanet.com/threads/diy-polyurethane-foam-winter-clothing.7705/