Import a representative project into Kdenlive: mixed-resolution clips, music, subtitles, and a few effects. Cut a short sequence, save and reopen it, render the delivery format, and inspect audio sync, color, text, and playback on the target device.
The project file is only part of the handoff. Keep media paths, proxies, fonts, and render settings with it, and test opening it on another workstation. Compare alternatives by the reliability of a real deliverable and the time spent fixing broken links, not just timeline features.
Akousa