I rode both bikes last year....ordered the Bottlerocket, should have it within a couple weeks. The Blur4x was smoother/faster on the groomed courses and uphill but the Transition killed it in every other way....Skills parks, slopestyle, pedalling DH courses, and all round general riding. And considering the frame is waaaay cheaper, it's the best option. Go with the Rocket.
If you are going to be hitting harsh slope-style jumps/stunts, then go with the Bottle-Rocket! The Blur 4X, is more for the smooth racer, just a little over built to save them from warrenties on those occational hard hits...
If you're wanting to hit nice slopestyle drops and jumps, and going to be ripping down trails, then I'd say without a second doubt, the Transition Bottle Rocket would be the absolute best buy for your money.