Seventh-day Adventism has two different "Last Generation Theologies" One which is very popular among our members and different so called "Historic Adventist" groups, including the understanding/teaching of M. L. Andreasen. This view sees the last generation reaching a different quality of perfection from any other generation, with the possible exceptions of Jesus, Elijah and Enoch. Also they tend to hold to a Greek understanding of perfection. There are at least some in this group who sees us as sinners because we perform the act of committing sins, and that perfection is no longer being a sinner for no longer committing sins.
The second view is not too popular in the church, but if you do a full reading from Mrs. White, you find her teaching this second view. For Mrs. White the last generation perfection is not a difference in quality as the popular view teaches, but she sees it as a difference in quantity, She sees every generation as having had a few people who have come to totally trust Jesus so that nothing can shake their faith. Some of our scholars have independently from each other noticed that, while she does not name names, her description is the same as how people had described John Wesley. I've also noticed similarities to the Norwegian religious figure Hans Nielsen Hauge. Her understanding of the last generation perfection is that many more reach the same trusting in Jesus that some of every generation has reached. Also, it's been pointed out that she does not use the Greek view of perfection, but a more eastern, especially Hebrew view where instead of a uniformed perfection, that it is being where they should be at their state of growth. Let's take a fruit tree for example: in early spring it is perfect for them to have buds. Then a little later leaves, and then blossoms, then the blossoms forming the early stage of fruit, continues to mature over the summer and early fall. In her view, we are sinners because we have the sinful nature. I think that she gives an excellent description of the sinful nature in her quote "There is in man a disposition to esteem himself more highly than his breatheren, to serve self, to seek the highest place and often this results in bitterness of spirit." Just because we become aware of this and examine ourselves to choose against this, it does not mean that we are not still sinners. Even our best is tainted with selfishness.