Yes, all of our backend features and functionality will continue working the same as they do currently, including our custom/third-party Integration feature ("Send transaction data to a URL" and "Payment Variable Information URL" as well as "Common Notification URL"), so you shouldn't have to change or update anything to keep that working.
The only thing we're changing is the frontend Admin panel you use to manage your settings, which will work with our existing backend as a drop-in replacement for our current Flash-based Admin panel. We are at least taking this opportunity to relabel some settings to make their purpose less confusing and more self-apparent -- e.g., "Send transaction data to a URL" will be relabeled as "Custom/Third-Party Integration", and "Payment Variable Information URL" will be relabeled as "Product Notification URL" -- but again, the way those settings actually function and the variable names they transmit will remain unchanged.
