For background purposes, I have held a CFI since 1968.
When I was with Civil Air Patrol we would give cadet orientation flights, and I would always let the right seater fly the airplane after takeoff. To keep it interesting, yet personal, I would ask him/her to show me where they lived. Some of them would be really good at taking me there and then back to the airport from where we came. I always asked each cadet if they had previous flight experience. Generally, the answer was no.
Thinking back to my initial experience flying an airplane with an instructor, I marveled at how good some of them were at altitude control combined with pretty good spatial orientation. Finally, the secret was revealed. Those who did really well were FS "pilots". How can any of that be a bad thing?
To answer the OP's question, in my experience flying FS dramatically aids in piloting knowledge, and if I were still a practicing CFI working for a living, I would welcome any student with FS time. Any experience related to flying contributes greatly to the learning experience and FS experience indicates a real desire to fly, which is a good thing for a student to have.
IMO...