Both impressive and the results of Atlas since operation shows it's doing a great job. A space-based telescope system would be able to do so much more, especially since it wouldn't have the limitations of only scanning the night sky that a ground one does. A key point - any impactor that is in a orbit similar to Earth's is that the last years of its path will be from the Sun side of the planet. The sooner we see anything and can calculate mass and vectors the sooner we can do any action that we might be able to do. Another key point - to be able to do anything like deflection we have to get to the object first long before its arrival, so knowing years in advance is crucial.