I've done a couple of very short term juice fasts - a two and a three day. The three day was 2 weeks ago and I loved it! The first day I had some slight headaches, but little to no hunger for the three days, and felt as good or better than with Water Fasts (without the usual miseries of strong headaches and hunger).
At the end of the fast I didn't binge like with Water Fasts and felt wonderfully cleansed. One odd thing I noticed was that my slight age spots completely disappeared after the fast.
Based on my experiences with juice fasting so far (and yeas vegetable no fruit), I have no doubt that doing a two or three day once a month or so would do absolute wonders for your health!