Tween works like an advanced Sine behavior. It's good for making nice visual effects, repetitive movements, animating scenery or UI elements. However, it's generally not good for use in actual game mechanics. For example, if you need to move an enemy sprite from point A to B, it will take a lot of efforts to make this work with Tween, you will need to experiment with different tweening functions, duration etc. And in the end the movement may still look unnatural and inconsistent. If multiple enemies started moving at different time/distance, they will all move at different speeds, unless you are using Linear function. Also, you have very little control of the object while it's moving, changing any of the Tween parameters will result in a very sudden change in movement, the object may even "teleport" to another location.
MoveTo behavior is more similar to Bullet, it provides an easy and predictable way to move an object from A to B. You can set acceleration, deceleration, current and maximum speed and the behavior will take care of the rest. You can change any of these values while the object is moving. Besides, it has a number of events and expressions, which don't exist in Tween.
Tween and MoveTo may look similar, and there are situations where they can be interchangeable, however they serve completely different purposes and can not be combined into one behavior.
A new 'Move To' behavior is now available in r166. Not only does it include moving to a position with acceleration and deceleration (including landing exactly on the target position), but it also supports waypoints, rotation, and following paths set out by a timeline, allowing for visual design of paths to follow.