Yep... :-)
I've never used one of those Bowflex things. Most of the "home gym" type equipement out there just isn't tough enough for serious use. I learned my lesson when I had a cheap Weider knock-off bench buckle under me. If it wasn't for a spotter, I woulda crushed my windpipe.
The idea is to slowly build up to 12 reps at a specified weight and then increase the weight when you can do the 12 reps with ease.
Unfortunately, I can't hold more than 70 lbs (my arms give out and I can't get the straps over my shoulders where they're supposed to be) so I can do 12 sets of 12 reps at 70 lbs and not even feel it.
It sounds like you're into serious weight lifting, so I doubt a bowflex is the right piece of equipment for you.