Your list is very helpful already since I've tried all of these roses, and none of the first four or Top of the World have ever survived for me at all in zone 5. That would make sense that if they're only root hardy in zone 6 they're not hardy in zone 5 at all. Tropical Lightning is going to be new this year so I'll give it maximum protection for as good a shot as possible.
In looking through my lists, here are samplings of climbers that don't survive for me at all in zone 5:
Blossomtime
Compassion
Papi Delbard
Joseph's Coat (surprisingly)
Annie Laurie McDowell
Mel's Heritage (but trying again REALLY protected one last time)
Raspberry Cream Twirl
Butterscotch
Candy Land
Creme de la Creme
Fourth of July
Gold Star
Guinee
Ilse Krohn Superior (tried several times, supposed to be zone 5 hardy)
Lichtkonigen Lucia
Night Light
Penny Lane
Royal Sunset
Spectra
Spice so Nice
The Impressionist/Apricot Impressionist
Valentine's Day
White Dawn
Apricot Sky
Pearly Gates
Just barely survives zone 5, but dies to the ground
Berries 'n' Cream
Dancing Queen
The Magician
Pinkie cl (needs my zone 6 pocket)
Olive
Renae (same - just barely squeaked through this year in zone 6 pocket)
Salita
Summer Wine
Coral Dawn
Frau Eva Schubert
Morning Stars
Pele
Eden (only blooms with surviving cane)
Ginger Syllabub
Jeanne LaJoie
Stormy Weather
Messire Delbard
Santana
Shadow Dancer
Aschermittwoch
Orfeo
Occasional canes surviving and reliably hardy, but mostly root hardy
Mme. Carolyn Testout
Harlekin (surprisingly)
Senegal
Viking Queen (surprisingly - supposed to be zone 4 hardy)
Victorian Memory
Polka
Dublin Bay
Louise Odier
Madame BovaryPinata
Purple Splash
Sombrueil
As for why the Explorers and other roses survive to the tips and the above roses don't, it's how they're bred. Some roses are simply more hardy and able to withstand low temperatures or temperature variations than others. It's the same reason we can't realistically grow most teas or Chinas in cold zones, or roses bred from tea/China heritage. They haven't had the hardiness bred into them, but were selected for other merits.
Cynthia
Q