We got the Tyrian 2.1 source to port -- the Tyrian 2000 source was not available.
I'm not sure why you think OpenTyrian is less smooth than Tyrian in DOSBox -- the framerate should be the same.
If you like Tyrian better in DOSBox, go ahead and use that -- I don't think you'll hurt anyone's feelings. OpenTyrian provides video scalers and a few bug fixes and runs on non-x86 platforms without emulation. If you don't need those, there's probably not much reason to use OpenTyrian.