Nmason,
I will check out the HG's again tomorrow. Optically they were quite pleasing. Again an extremely large sweet spot but definitely not sharp edge to edge. I would believe the field flattener claim based on edge performance. Like I said I'll try it again tomorrow and see what like I said I'll try it again tomorrow and see what else jumps out at me. They do have the super smooth, almost buttery, Nikon focus.
Thanks!