Stretch with bigger blades and longer boom will rob you of power. That big of a disc created more drag, and motor will have to work harder to keep those blades spinning against drag. If you want more stable nimble helicopter, stretch is just what you can do.. But if you are 3s setup, and you stretch, you are going to see slower response times and more sluggish bird. Not always a bad thing. If all you do is putter around and slow rolls and flips and just relax, that's just for you .
If you upgrade to 6s setup also, THAT will make it a power monster. And yes even before the 450L dominator, people out 6s setups in align 450's and those birds were angry!! And tons tons tons of torque
Just good for thought