Mike,
Without a doubt the sand based tee will be subject to more low temp kill because of the increased air space between particles, in comparrison to soil based tee. Being in área subject to potential deep or prolonged freezes certainly tilts the scale in favor of a soil base. However in Central america or other áreas not subject to deep freezes I think you should continue with the sand based tees.
Topdressing divots material should depends on the base material. Many get better results with topsoil because it doesn´t dry out as fast as sand thus a better chance of higher percentage of germination. However, using a topsoil on top of a sand based tee will créate a potential long term layering and deminish water infiltration rate.