The rainfly arrangement works quite well, and has done so for years - one of the reasons it is so popular. Most fit quite tightly, and are not a problem in high winds. They give solid rain protection, good ventilation, and just a smidgen more insulation.

I am talking of the full coverage rainflys, not the dainty handkerchiefs that some cheap tent provide.

Some tents now have the ability to pitch the rainfly separately from the tent, if weight is a concern.