Puffkit, I grow several kinds of Osmanthus in my garden, and I can share my experiences with you. The hardiest for me has been O. heterophyllus 'Gulftide' -- almost no damage at all in the last 20 years. Another that has done very well in terms of hardiness is Osmanthus sasaba. Osmanthus armatus is a third that can handle 6b. No real damage to any of them after a spring of alternating warmth and freeze.

Osmanthus fortunei often takes a beating in the winter but fills in well later and keeps on growing. I like it, and I just accept that it really isn't a true evergreen in my area unless it is quite protected.

I have Osmanthus variegata in a protected area, and it still suffers in a rough winter, but always comes back. The Goshiki, which I have only had for 3 years, seems to do better. They are both very slow growers.

Osmanthus americanus usually doesn't have dieback for me, but this spring has produced more damage than I have every seen before on it.

Osmanthus decorus 'Baki Kasapligil' is the closest I have to Osmanthus burkwoodii. I have lost two to deer since this Osmanthus lacks the shiny, sharp leaves that protect the others. The one I have now is next to the house in a warm spot and doing well.