Yes, it is just for grass. I need to do a lawn renovation. I am planning on picking up an aerator. The walk behind slit seeder are horrible. I have rented them a couple of times for overseeding and did not have good luck with them. I do not trust them for a lawn renovation. Broadcast spreading would be a waste. Trying to find a way to get good seed to dirt contact without having to till the yard do to an irrigation system.
Here is an option that you may want to consider if you are willing to dish out some $. http://www.fergusonmfgco.com/aerator_products.htm. If you email these folks they'll give you a quote on shipping and you can specify which drum you'd like on the equipment (slicer or core). Everything I have read leads me to believe that slicers are bad. I was quoted around $1600.00 for a Yardmaker with the core drum shipped to Maine. A little more than I wanted to spend especially since I just invested in a decent broadcast spreader. I've ordered an aerator from Wicko http://www.wikco.com/Turfvent.html. They look solid enough for my home application. More rugged than an agrifab or brinley, but probably less so than a frontier or land pride. With so many options out there for aeration, a decision was tough. But I bit the bullet on this one and we'll see how things work out.