I have not compared the VSIs but I concur that stopping a fixed pitch prop requires a speed very close to, or in my case (R2160) even below Vs. Getting it to windmill again required around 140 knots.
In an emergency I would not consider stopping the prop, partly because of the high rate of descent at Vs, or the maneuvering required to get below Vs (basically a ballistic flightpath) and the mental energy that takes. Much better to spend that time and energy finding a suitable landing spot.
But a second consideration is that a windmilling engine *might* spontaneously restart itself. (For instance, just suppose there's a slug of water in the lines or maybe vapour lock. With the engine running it might eventually be sucked through.) But a stopped engine definitely will not.