Working in weatherization,I would'nt install anything but blown in attics,specifically cellulose.If you were to crawl into an attic with a thermal camera and pressurize a house,insulated with batts you will find leakage at every seam,and alot no matter how good they are laid in.
Cellulose is ,cheaper,has better air sealing properties,does not itch,and no voids in your thermal boundary when installed properly.
Personally the only time I would even think of blowing fiberglass would be areas where wieght or possible moisture issues may arise.
As far as ventilation goes,that gets trickier,venting for southern climates is very different than our northern climate,where frost and freezing temps become an issue,an attic loaded with chutes or whirly birds and poorly installed insulation is a recipe for disaster(that will probably piss off every roofer that reads it)but it all goes back to pulling warm moist air up through a cold attic=frost build up,ice dams,spring floods.