Clarification on PowerStore Gateways Supported
To clarify, the posts that Jason Byrnes detailed in the thread you link to are correct. While you could change the PowerStore to use a different gateway, you would lose a lot of functionality (such as inventory control) with some gateways (like PayPal Payments Standard) and would have to hand-code that workflow if you wanted that to work again.
PowerStore v2 is meant to work with PayPal Payments Pro and Authorize.Net. Should you want to use PowerStore with other gateways, there may be limitations, such as needing eCart or hand-coding. Anyone is welcome to contact us via this forum if there is a gateway they are considering switching the PowerStore to. We can tell you whether it's easily done with eCart, whether you'll lose functionality even if you do use eCart or our perceived level of difficulty to accomplish what you are looking to do.