IMO the NTV is the other decent mic that Rode made, appart from the Classic 1 and 2. They discontinued it because it was priced very close to the Classic 2 but doesnt have pattern switching/pad/HPF so people werent buying them.
They 'replaced' it with the NTK which is a very different mic, much cheaper and far less useful, but sadly ubiquitous because of its low cost. If you ever see a cheap NTV going, theyre worth checking out.
Like they said above, the NT1 is a completely different mic and has had many incarnations. I would have thought that replacing the electronics with a tube circuit would be difficult because of that big thick PCB that fills the inside of the mic, covered as it is in surfacemount parts.
M