Steve,
Thanks for the info. I am good to go on the tanks, I bought a pair of PST E8-130s this summer. I had to have them shipped from Florida, but it was worth it.
The great lakes have some of the best preserved ship wrecks anywhere and Lake Eries shallow depth puts a large number of them within the recreational limit. There are very well preserved wooden ships from the 1800s as well as some fairly large freighters. The zebra mussels have been a mixed blessing to us, they have greatly improved visibility, but now cover most of the wrecks. I have been to some wrecks diving with osprey charters out of NY where visibility was easily 70 feet at the bottom.
A drysuit is definitely a good idea in the great lakes. I have dove a 7mil wetsuit in water down to 45 degrees in lake erie at various depths. It was fine down to about 70-80 feet, but the compression of the wetsuit really reduces its insulating properties in deeper water. The biggest problem I had was with my hands and switching to a 5mil glove really helped a lot.
I just got a drysuit from divetank.com this winter and I have been testing it out in the quarries, while I wait for lake charters to start up again. With the proper undergarments I was comfortable in 40 degree water, and the surface intervals are a picnic compared to freezing in my wetsuit.
I highly recommend divetank.com for getting a drysuit, they have a great guarantee on fitment and great prices. I tried to work something out with my local dive shop, but they could not come close on price or guaranting the fit.
Mike