The Scheduling from ACSTG is a part of the Work Order Efficiency package I believe. We have several clients actively using work order module in Sage. The ACSG Work Order Efficiency package is something we look at for most of our work order clients, and we have installed it at several places. We don't have a lot of clients that have purchased the scheduling package. I would recommend that ACSG does a demo of how the scheduling works and make sure it fits your clients needs.
Keep in mind that Sage has finally announced that they are rolling work order module up business object format sometime in the next couple of years. (version 2018 is the last I heard).