Lets do the math again:
For the ZT0551 vs. SNG:
5.8 oz.-4.5 oz.=1.3 oz.=37 grams=7-8 extra nickels. Nickels are 5 grams each.
At work, I have to carry a large key ring in my left pocket (with flashlight) and some pocket change, knife in right pocket, wallet in back right pocket and a pouch with a few tools on my belt. Even with a 4.5 oz knife in my pocket I get chafing from all this crap pulling my belt/pants down (this isn't a pretty picture in the workplace!) throughout the day since my day doesn't involve sitting at a desk for 8 hours. At work, I am walking for 8 hours/day SOLID on hard surfaces wearing safety boots/shoes. So anything to lighten the load is welcome. Otherwise I would have to wear suspenders!
I decided to draw my line in the sand at 5 oz max, which is about 2 oz more than I would really like to be carrying. If I am home inside the house the extra weight is not a factor and I occasionally sit around with an 8 oz. knife in my pocket. I admit I could certainly use a trip or two to the gym but strength is not a problem...I am 6'3" and well over 200 lb. I also have real big hands and as a result of all this, I prefer knives with long handles but light in weight. The Spyderco Military fits me in hand and it is also within my desired weight, but unfortunately I need to carry my knife deep in pocket without the clip and for this type of carry, the Military's handle is too long. I wish all knives would work for me but unfortunately with my hand size and my work situation, my list of suitable rugged production folders is very short.