Scott,
I purchased a Grate Poker tow behind true core aerator this summer to use this past fall. I also purchased a hitch kit from Toro to tow it behind my Toro Z Master. As with most tow behinds, it has it's quirks but I am 100% happy with it's performance. You have to be careful with your turns or you'll tear some turf up. I have it completely filled with water and the soil penetration varies from lawn to lawn. I purchased the 36" model at the advise of the salesman. I thought getting the 48" model would cover areas faster but he was correct in saying the larger the unit, the bigger the turning arch needs to be. As for how fast you can go, (again on his opinion) the faster you go the better the penetration. When you slow down or stop, it lifts out of the soil sometimes. Our properties vary in size from 4000 sq ft to 30,000. It works awesome on the larger wide open lots. On some of our finer homes though, we still use a walk behind aerator unit that we rent. I paid about $500 including shipping for the unit which was beefier looking than I thought it would be. Their web address is
http://www.7315.com Get the heavy duty transport wheels if you go with this unit for the constant ramping up your trailer gate it will encounter. I am very satisfied with it and it has already paid for itself 10 times over just this past fall.
Mike