I'm going to take the other end of the spectrum and say that what systat has done is simply incredible. Personally, I always thought you'd have to be a complete MORON to bet unders in baseball of 7 or 7.5 (or 6.5...wtf!?)
But systat has made it work for him up to this point, and he deserves credit for that. I am usually very hesitant to pull the trigger -- and luckily avoided some of his recent plays -- but he has had success and I will continue to monitor his thread in the future.
My main worry with playing unders that are so low is two-fold:
1. Early offense; pitcher gets shelled; you're fucked
2. Messy bullpen work
The flip side of that, of course, is those beautiful three up, three down games, where both pitchers get into a rhythm and you know the game has no chance of reaching even five runs.