1.5 for 3D is like the minimum (if possible) ... x2 is heck of a lot of fun, then we are talking about being able to punch out of a prop hang with a lot of authority. I am gonna test the amount of thrust on my F90 with a YS110 but I suspect that I am getting about 16-17 lbs thrust. The plane is about 9.5 lbs. Hence I have about 1.7:1 power to weight ratio. The plane hovers at 55% throttle but I would love to see her punch out much faster. If only I had like 1.8 or even 2 times. For me its about the thrust for uplines ... love to see a plane climb forever and able to pull nice big loops with ease.