The mistake to avoid is treating TSplus as one product to clone. It bundles remote sessions, application publishing, browser access, gateway behavior, user mapping, and an admin console into a single commercial surface, and open source rarely packages all of that together in one place. Decide which part is actually critical - full desktops, individual published apps, browser access for contractors, or an internal help-desk tool - because the replacement usually splits those roles across a gateway, a session protocol, an identity provider, and separate monitoring.
The real loss when you leave is polish around the all-in-one experience. Moving off TSplus means more manual configuration and more responsibility for testing printing, clipboard, drive redirection, file transfer, MFA, and load distribution yourself. A browser gateway such as Apache Guacamole handles standard sessions well from any device but can feel different for graphics-heavy apps, while a tool like RustDesk gives full remote control of a machine rather than the seamless single-app publishing TSplus is known for. Plan for user retraining and a longer validation cycle than a simple client swap.
Migration begins with an inventory, not an export, because no TSplus configuration converts cleanly into another system. Document your servers, published applications, user and group assignments, gateway URLs, certificates, MFA settings, and printer mappings, then rebuild the access rules in the new stack by hand. The applications and user data usually stay where they are; it is the shortcuts, portal links, and device-redirection rules that need cleanup. Run a pilot in parallel, move DNS only after testing, and keep the old endpoint reachable until rollback is no longer a risk.