I have a few sets of IW bands. I've had them for about a year and a half, they have held up well. Woody makes a fine band. However, I suspect you would have to torque the hell out of them to get to the higher number they give as its resistance range. I have some of the black bands.
In using them in squat and with the bottom choked around dumbbells on the floor, I figure they are about 100 lbs each at the top. My green bands, set up the same way are about 80 at the top. (I am about 6 foot 4.) This is pretty consistent with how the comparable Jump Stretch bands are- i.e. IW green is about like a JS green, IW black is about like JS black, etc. Maybe if the bands were doubled you could get to the top values that IW boasts.