Leaf color will definetly vary from year to year, more particularly so in the first few years after transplanting.

Mature trees(10+ years in the ground) almost always sure stronger, longer lasting fall colors then newly planted trees.

Trees really do get better with age.

Seedling trees do vary, some are better looking than others, just like people.

The Sugar maples in my area turn a warm nice yellowish with a hint of deeper color usually. Named clones should be more consistant.

I have a tree that I was sure was a sugar maple but colored an OK yellow at best. I had someone take a look look at it and they though it might be a black maple also. The local sugar maple generally have great color in contrast to my tree. If you are purchasing a maple for its fall color my advice would be to purchase it when it is in fall color or to purchase a named cultivar known for great fall color.