First of all, 14 pounds isn't bad. You have to be careful of the perspective here– there is ultralight and then there is crazy-light :) 5 pound base weights aren't for everybody, every season, every climate or local conditions. Hike thy own hike!
As to your shoes, when you get into running shoes, you will see that each model is made for a particular kind of runner and helping to correct how their feet hit the ground– over and under pronating, etc.
Since you will be walking, this may change a bit. I would love to hear the ergonomics of choosing running shoes for walking. IMHO, I think we choose trail runners because they are the lighter and more cost effective alternative– and we can get them to work. There are a few manufacturers who make lightweight walking-specific and load bearing shoes. Montrail is one that comes to mind.
This is complete armchair quarterbacking, but I imagine that you could get an idea of your walking style (pronation, etc) by looking at the wear on your old shoes– looking at heel wear and so on. This might give you a fighting chance in getting a trail runner that suits your walking style. A good sports shoe salesperson will know the brands and models that will help you get a good stable platform. You will find this information on the better web stores too.
My daughter does cross country running at school and we went through this to get her a running shoe that suited her non-average foot and gait issues. We're blessed with a number of excellent running stores in the area with the staff and inventory to dial in a shoe for her needs.
I think the UL industry really needs to develop walking and load bearing specific shoes. Trail runner construction techniques and materials certainly make sense, but I know that changes can be made in the rocking motion of the sole, traction, protection, heel construction and so on to maximize the shoe for UL hiking.
In the case of the 872, I found a consumer review at http://www.roadrunnersports.com/rrs/products/NBA1240/ that descries this model as neutral ergonomically. Try surfing "new balance 872 review" to see what you can find. There is a BPL spotlight review too (http://www.backpackinglight.com/cgi-bin/backpackinglight/new_balance_872_off_road_trail_shoe_spotlite_review.html). There is an interesting review of New Balance trail runners as walking shoes at http://walking.about.com/od/prshoe/tp/nbshoes.htm?terms=new+balance+hiking+shoes .
I also wonder about how shoes are made in such a wide range of sizes with the same materials and construction, where they will be worn by say, a 5'2" woman who weighs 120 pounds and a guy who is 6'6 and weighs 220 (loose examples). I wonder what the impact pressures and other physics come out to between these ranges. The variations in gait due to leg length, hip width and dozens of other ergonomic variables. I run into this myself as I'm outside the bell curve, being 5'10" and a 30" inseam, so my stride/gait is much different from someone who has say, a 34" inseam.
I'm all ears to what others here know about those issues.
[exit soapbox mode]