Both versions of the song are pretty good IMO.
In fact, the original (demo) version they played live at the Mtv Music Awards in 1989...was the only time that they played it live with Steve Clark.
Which if I am not mistaken...was the last time Steve Clark played with the band in any live capacity before the band went on hiatus and started their break and doing pre-production for what would be Adrenalize.
Unfortuantely - Steve passed about 2 years later.
Here is the video.
Def Leppard - Tear It Down (live MtvVMA 1989)