Pat,
Greenkeeping has changed immensely over the years, from topdressing practices to mowing equipment to rolling practices, verticutting, etc. Don't attribute all the improvements of the current greens over the old bermuda greens entirely to the conversion to bentgrass.
Perennial ryegrass, the type that Augusta and most other southern courses overseed fairways and tees with, are genetically bred for dark green color, and apart from certain Kentucky Bluegrasses, there's no darker grass. They are a much darker green than bermudagrass.
Arnold Palmer probably doesn't have to slam his putts as hard on the modern bermuda grasses under modern maintenance techniques, so once again, don't give all the credit to bentgrass.
I don't know what Augusta's budgets or quantities are for input materials (fertilizers, pesticides, etc.) but a great deal of the courses' appearance is attributed to meticulous detail in the labor efforts. The perfectly edged bunkers, the lack of debris and litter, and even the pond skimming with swimming pool tools all adds up significantly to the presentation during Masters week....above and beyond fertilizer and pesticides.
Joe