Chip
I have not used the machine, but after reading on the website I would like to see it in action.
As for the old way of aerification, it depends on what one is trying to accomplish by aerifying.
USGA recomends removal of %20 of the turf from greens annually. The dryject will not remove any. It appears to shatter the ground with water (like the old hydroject) and fill the hole created by the forced water with sand or what ever material you want to incorperate. It can not be compared to traditional aerification that removes material, but does look like neat tool. I have used the hydroject in the past which was a troublesome machine and did not have great success with it.
MR