I did not use VDJ yet for VJing, but I have set up some projectors and it largely depends on the venue what you need. The rule is: The more lights the venue has, the more lumen you will need to still have a decent colored picture. So my current setup has about 4000 lumen. However you can get away with 720p resolution easily if the screen is not overly big (aka over 4 meters width).
I really liked Sanyo projectors as they seem to be much bang for the buck and since setup is often a question, the Sanyo seem to have the best lens shift in both vertical and horizontal direction.
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