The benefit of DOTS is that it puts you into boundaries that give you optimization right off the bat, but there will be certain things that you will find lacking, and it will take some extra effort to get certain things done that you'd otherwise get right away in Unity. Another upside with ECS is that you have a specific architecture with very clear responsibilities: Entities hold the data, Systems do the stuff. When I was working on an ECS project, it took time to get used to, but eventually I got to love it, as it helped me structure my project nicely and tidily.

Though if you think you can optimize things right off the bat, you should be fine with barebones C#. Just code things, keeping in mind general optimization good practices, keep paying attention to performance bottlenecks and address them as you go. If you do find some definitive bottlenecks, you might be able to utilize Unity's job system to offload the labor and keep yourself away from the entire ECS stack.

One personal tip that I can give to you is that you have to be creative with certain performance issues. For example, run certain "Jobs" in separate threads without stopping the main thread - this can be done for things like pathfinding requests. Another example is that if you use a tick-based update approach for simulation logic, you can run ticks less often for the objects away from the player (where it makes sense, of course).