We aren't using Inventory, just AP. PO is just an extension.
One thing I strongly recommend is using the GL stamp rather than the side-by-side (SBS) integration in PO and AP. We have seen real performance issues with SBS that stems from calling the Altec process from within a script. The GL stamp process works much more smoothly.
Also watch capturing AP checks. It usually works very smoothly. However, our last implementation involved a customer with both a physical device for MICR encoding checks and a software process to put a 2D bar code on the check that replaces positive pay. The software if from their bank. With check capture by Altec, we had 3 different processes to orchestrate after Sage 100 actually produced the check and sent it the network printer. Needless to say, there were some hurdles to jump.