I have an Aera-Vator AE-40 tow behind. It is wonderful. We use it on properties that are extremly compacted or very rocky (you know the ones, where the walk behind aeraters bounce across the turf). It works best in dry conditions, if it's very wet it makes muddy holes in the ground that last forever. It's worked miracles for us. I give it my highest recommendation.
I've got the 40 inch aera-vator for the grasshopper. I've got Bob's old 725. I put electic lift on it. Kinda hard to get connected. Not alot of time on the unit yet, seems to work well. The ground should be dry for better results.
my landscape material supplier has one. A 40" model. He said it was worth the money. He stop cutting grass, but keeps it around with one lone grass hopper for his own house. He said you need the powered lift. Its on a 721D.