The 1-KZT engine is about as bullet proof as you can get. Mines done 155,000 miles, doesn't burn oil or use water, starts instantly and runs smoothly from cold. It's emissions on the MoT test are well inside limits. From info from others with this engine, my experiences are normal.
The "E" series engine has no more power and torque, and according to one source, the electronics were fitted so that the engine would be more acceptable for use in the Colorado (90 series). Apparently the "judder" when you switch the engine off on a 70 series was considered detrimental to Colorado sales.
Roger