Transition from copes to slate

[Kilt]

In Scotland, what would be the recommend, most robust finish for transition from cope stones to slate?

 

Seems similar arguments for a skew fillet over soakers or a Watergate, with cover flashing under the copes, leading over the soakers.

 

I have the option for either, we current have soakers and fillet and live in a VERY exposed location. A fillet seems more robust to the wind, than flashing. Am I right in thinking when applying fillets, they should not be in-contact with the slate during curing and be separated by paper/felt/greaser. Metal lath can be added for extra strength???

 

Any advice would be appreciated.