As was stated, most 1911s are not fitted very tight right out of the box and it takes some $$ to put the high end parts on them and only you can say if it is worth it for you to spend the cash and realize a fairly small return on investment.
Practice, practice, practice. Remember that in most circles, 21 feet or 7 yards is considered to be average self defense range. I'm pretty new to IDPA (international defense pistol association) shoots, but in the two that I have done, we have not gone beyond 20 yards yet.

On another note, I bought a Kimber .22 conversion kit that fits my 1911 and man is it fun to shoot. Same frame, so same feel in the hand, but much less expensive to blow through a bunch of .22 vs. a bunch of .45.

Good luck.