I think a lot depends on how long they are and how you use them. They are quite strong for the weight. I often put all of my weight on the pair (to basically jump down from a higher point). They work fine for this, even when set pretty long (I like to have them sticking way down the trail). If you shorten them up, then they will be stronger. In general, though, I think if you use them carefully, then they will be fine (I don't, but I'm a lot lighter). If you are tall, then you probably want them relatively long (unfortunately).
I like the other suggestion of getting a fixed length pole (if that fits your style). I think you might be able to get a fixed length pole (G3) combined with the outer pole of a G4. I would imagine this would be very strong. In general, I think this would be a nice market, for those that are worried about carbon fiber. A pole that is a bit heavier, still lighter than just about any pole out there and extremely strong might be quite popular. In some ways it is like 1.5 ounce Cuben (extremely strong for the weight). I would definitely talk to Glen about this. One of the great things about these small shops is that you can talk to the folks who design and make the gear (unless, of course, they are out hiking).
Assuming you only have what is available, I would still get them (assuming you can afford to take the risk). I've found that as your gear gets lighter, so do you. If you carry lighter stuff, your exercise becomes more aerobic, and less anaerobic. Instead of carrying a 40 pound pack 8 miles you carry a 20 pound pack 15. In other words, you go from being a lineman, to a linebacker, to a defensive back. With a few beers after a hike you can even become a kicker. :)