I disagree a little with the other authors in that the term "bottoming-out" can be applied to reductions or augmentations; in fact, in my training, bottoming out was one of the concerns in terms of judging breast reduction shapes in comparing vertical with standard techniques. But that is semantics.
Basically, what you want to know is whether your lifted breasts will stay lifted, and for how long. The answer is, like most things, it depends. It depends on how much skin excess you have in the lower pole and how elastic vs. stretchable it is (note: elastic is NOT the same as stretchable; in fact, they mean opposite things). If you have a mastopexy with a vertical technique, the length of the vertical limb from the bottom of your areola to the fold may lengthen with time as the breast tissue hangs down (like an implant might) into the skin of the lower pole.
An exam is required to assess how loose or stretchy your breast skin is, and to determine what incision approach you need to provide adequate lower pole support to your breast tissue. All lifts involve a slight reduction, actually; you have to take skin and some soft tissue out to shape the breast. So it is semantics in a a way, but the term reduction is typically used to describe a significant amount of breast tissue removal.
Get another opinion or two from board-certified plastic surgeons before you decide. Good luck!