I have both Dicksonia antarctica and the Eriobotrya j. (loquat). I have overwintered the loquat outside next to the house successfully (don't know about zone 6)--but zone 7 also gets mighty cold. Mine is now containerized as I'll be moving soon. Haven't tried the antarctica in the ground yet. They are so rarely available, I wouldn't want to loose it--so right now it's strickly containerized. What can I say--I have lost enough marginal plants to make me very conservative about pushing the zonal envelope. Also, our climate is soooo weird now--totally unpredictable and every season seems abnormal in one respect or another. Don't know about the other plants but these two are very robust and attractive.

Thank you njoasis.I guess I will do the same. I have great spot close to the house where I can try Eriobotrya. I will try to keep Dicsonia inside as a houseplant.

Eucomis montana-Eucomis I've tried are hardy in well-drained soil with mulch.
Edgeworthia chrysantha -no damage near zero;full of flowers!
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Arbutus unedo Oktoberfest-Haven't tried
Illicum henryi-no damage at -6F in 1994. Should do well in zone 6 along with I. floridanum.
Dicksonia antharctica-survives with heavy mulch;not really hardy.
Agapanthus Peter Pan-Agapanthus hardy with mulch
Eriobotrya japonica-I lost mine in the lower single digits. Hardy to 5.
Carpenteria californica-haven't tried

Thank you Steve, great help. I think I will try again Eucomis this year. I lost E. Sparkling Burgundy but didn't mulch. I will probably bring Carpenteria, Dicksonia and Arbutus inside.