What should I consider when choosing a pocket door system?
There are a number of pocket door appraches. Usually is makes sense to buy a frame kit such as this one



There are many grades and sizes, some of which are meant for heavy doors. You do need to make sure that the thickness of your doors do not exceed the limits of the kits. If they do, you may be able to buy parts and create your own combination that will suit. Also, there are standard heights, which could be adjusted for (e.g., with bottom blocking) if your doors are especially tall.

There are other brands that may provide additional features, such as this one which has a color matched header insert, and this one which can be used in thicker walls , and perhaps with thicker doors.