I have also tapered my main at the GC and can now easy sheet without cleating with a 8:1 main. Tapering makes a big difference.
I also think 8:1 gives more control and my ideal situation is the crew doing the main at 8:1....

Concerning the F18, I had the idea that Aido was keeping up well with most of the other F18 (Ofcourse he is used sailing mixed while most of the other mixed crews weren't because most of them sail with 2 men).
Again, most will depend on the skills...

Gill