We are making a Autonomous flier (quad rotor based) which will carry Sensor system(LIDAR,INS etc) and a camera; and is capable of obstacle avoidance and precise hovering.
We have narrowed our search for a quad rotor flier to 'X-3D- Scientific' as our base model of which we will change motors,propellers and battery.
We plan to change the motors with Hacker A 20-22l outrunner and the standard propeller of 10*4.5 and also the battery with a 5000/6000 mah for higher flight time (about 10 mins).

Certain queries:
1. Will the flier with new configuration and total weight of 1433gm produce enough thrust (about 1.8kgs) ?
2.Is X-3d best one around?
3.Do we have better motors (producing more thrust ) ?
4. Is 6000 mAh correct estimation of the Battery type?

Sounds like a fun project. Those motors are good. In my 700g plane the A20-26M, 8x4E prop gives me up to 20 min flights on 1200mAh from a 1550mAh 3S1P LiPo. I would recommend starting with a smaller prop, an 8x4E or 9x3E or SF. You should be able to hover at about 6 to 8 amps per motor, 8 min with a 5000mAh. Don't go over 10 amps (120 Watts) with these motors.