Hi,

actually there is a third method:
Take a double braided line and remove the core. The big advantage is thet the transition point is very smooth and it is done very easy (no splicing, no tapering).
Liros offer a sheet called Magic Sheet 7 or 9mm with a PP core and Lancline in various diameters called Diminution.
Liros Lancline
Actually you can take any double braided line, but if the core is stronger (e.g. dyneema) than the outer braided, ropes tend to kink or curl, ones a high load was applied. Something I learned from Dinghi sailors and it is true.

I use currently 7mm and think that is ok, if your main has not more than 15sqm. But agreed, it is pain in more than 20kts of wind. I guess 8mm is the good number.

Cheers,

Klaus