Ridin' makes a good point. A more powerful blower will not only do things faster, but it can do things that a less powerful blower just can't. Those branches that you can't move and need to pick up by hand, the leaves that you can't easily get out of the pachysandra, the wall of leaves that is no longer moving, working in the rain sleet and snow (yes, I've done that) when otherwise you'd just wait for better conditions.
I bought my 580 as a cleanup machine but found that it saves me a lot of time on the mowing route too. If I put an extra intermediate tube on it which helps focus the air stream, I can literally blow clippings off pavement from 30 feet away...a bit less in the factory configuration. I like to leave all hard surfaces spotless and on some accounts with large parking areas and turn-outs I'll just stand in one spot and swing an arc with the blower and be able to clear the whole area without moving from that spot. I don't know about you guys, but what gets me at the end of a long day is my feet, so the less walking the better.