Gary:
I think we had a D-5 and a D-6 at Ballyneal. The D-6 was for doing larger fairway work, but some of my associates are just more comfortable on the bigger machine and they can still do the little stuff on the greens with it.
As to the greens, we build the cored-out shape right away, instead of building the green at grade and then coring it out later. We feel like we are good enough to visualize how the tie-ins are all going to work, but nobody's perfect -- we're all better in sand where you are building the finished surface with the shaping machine, as we could do at Ballyneal. Those aren't USGA greens, they are native sand.
Personally, I've never gotten much done with anything bigger than a D-5. I learned on a D-4 and I got used to feeling what I was doing by whether the machine was slowing down a bit from carrying too much dirt on the blade, or because I was going uphill. On these new, powerful, enclosed-cab machine I can't really feel what I'm doing and I'm not very good. In golf parlance, I'm about a 10-handicap bulldozer operator. If I made time to do it more myself I think I could get back down to a 4, but I'm not really motivated to do so when I can call the shots for a pro instead.