Flavor or not for this port?

[L.Bartoletti]

Hi,

I want to take x11-toolkits/qwt{5,6}-*

Both are built for Qt4. I especially need qwt6 for Qt5. Since we have 
flavors. Is it better to add a Qt5 flavor for Qwt6 or simply add a 
x11-toolkits/qwt6-qt5 (like security/qtkeychain-qt{4,5} ?)

Thanks.

Regards.

Loïc