Serra.. I have to say you know your stuff! So i'll just say the same thing Serra said with a different twist.
IRIS is an incredible feature with Iris pulse and being able to pinpoint objects. So the Power Spot 575IE gives you that option.
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The Power Spot 575ie literally weighs 42 lbs. This fixture is so light to hang you want to hug it. This is because it has a multi voltage electronic transformer, so you can plug it in 220V or 110V and it auto senses the voltage.
If you ever run 220V you can plug 4 of these on 1 circuit freeing up a lot of 120V power.
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The Design Spot 575 also has an Iris. But I really apreciate the Zoom. Zoom!!! this is not common for any 575W fixture.
The unit weighs about 65lbs and it does make it heavier. But you get Zoom, and animation.
Many times you may not need these features, but it is really nice to have them when the oportunity presents itself.
Animation is nice on static looks.. you don't get the rotation effect, but you get a good texture effect, Oh, and it's also available in white!
Best regards,