The short answer is yes, using live view is the equivalent from a mirror movement point of view as using mirror lock-up. (The mirror doesn't drop again).

However in the normal live view case the shutter curtain must reset before the exposure can begin. This results in one more mechanical action than just using mirror lock-up and not live view.

Additionally on many camera's (including your 70D) you can use electronic first curtain shutter (EFCS) when in live view. This reduces the vibration even further by only actuating the mechanical shutter at the end of the exposure. On Canon camera's this is normally called "Silent Mode 1" in live view.

In-camera vibration can be a concern for sharpness and is generally most visible at certain shutter speeds and/or orientations. The tripod/support system generally does not have a huge impact on damping in-camera vibration. i.e. even on very good tripods you can still measure the effects.

Of course whether you feel this is important to your photography is whole other (very subjective) story, ultimate sharpness is not necessarily what makes great images.

Some further reading:

http://krebsmicro.com/Canon_EFSC/index.html

http://blog.kasson.com/?p=6731

http://blog.kasson.com/?p=5402