Pay... I've tried both kites and I really enjoyed the Nano previously. Give the Renegade a try... but wear a helmet because your head just might explode. It's fantastic.
My riding style tends to lean towards the Renegade vs the Screamer for me. I like the Screamer for snow kiting (great upwind) but for me.. I'm all about the Renegade.
To tune it... I rig the kite, put the two front lines one knot towards the bar (by mickey mouse ears) and ride. I never have a need to fuss with the strap or anything. In sufficient wind (11 knots) the kite doesn't stall on me. 15 knots seems to be the butter wind.
Looking forward to her what you think about it when you give it a shot.
take care