Flop a set 1 out of 8 times. $2 (4BB's) x 8 = $16. So you must win at least $16 (32BB's) each time you hit to break even. If it's just heads up I'm not sure if this is happening often enough to be profitable. I'm not saying it doesn't happen enough...just that I'm not really sure. What makes this profitable vs. full stacks is that when you stack them for 100BB's that covers a lot of ground. I think the 10x rule is pretty insane though. If you are regularly calling 10BB PFR's against fellow full stacks you are paying a pretty penny. At this level that would be a $5 PFR. So $5 x 8 = $40. So you'd have to make 80BB's each time you hit just to break even.