Long answer alert...
I have been doing simplefit about a year. I have done a lot of other programs, but none as consistenly as this. IMHO, if I do simplefit the way the program is intended, I have very little energy left that could constructively be directed towards free weight training. Try doing just s/f from level 1, giving each workout your all. Then honestly consider if you wouldn't be overtraining by adding free weights. You may have specific goals that require the skill practice or emphasis that free weights can provide.
After a year, I definitely don't have a build like a bodybuilder. I am thinner, fitter and stronger than 90% or more of my peers. I can run as far as I want, bust out pull ups, one leged squats and hand stand push ups at the drop of a hat to win bets and amaze my wife. The time investment is minimal, the equipment sits atop my garage fridge when not in use (a door mounted pull up bar) and my 14 year old can do it with me.
It's a pretty good program that stands on its own, depending on your goals. Hope this helps.