Re: Polar Lights NX-01 "Refit"
The refit is named the "Columbia Class" and both the NX-01 Enterprise and NX-06 Endeavour have been refitted to it during or after the Romulan war.
According to the 15th Enterprise novel, the first in the "Rise of the Federation" series as part of the novel continuation.
So it's as canon as the novels that are continuing the Primeverse.
It's not specifed in the novels whether Enterprise get's the refit - I checked with Christopher who wants to leave it to the reader to decide.
He likes to think it did though...
Soon oh soon the light, Pass within and soothe this endless night, And wait here for you, Our reason to be here...