I wouldn't recommend it even if it were free. It would be a downgrade imo; more inertia in the driveline would reduce acceleration, you'll be wearing down the teeth on the clutch bell more quickly, it'll be louder...
I read an interesting breakdown of metal to metal, plastic to plastic, and...
Sounds like the one-way-bearing for first gear is going bad and slipping, especially since it's fine once second engages. Can probably replace just that part and you'll be fine.