Somewhere in all of these posts, we explain some of what you are asking about. We use to belong to a Star Trek Fan organization known as the IFT (International Federations of Trekkes). Their fictional side if you will, was the (Intergalactic Federation Taskforce). While the ships were in some senses part of Starfleet they were in a separate division, handling more dangerous missions, recons, getting needed medical supplies to certain areas, surveillance, missions and the list goes on. So some of the ships were more heavily armed then others. At the time we were NFC instead of NCC meaning we were part of Starfleet in ways just not sanction by Starfleet.
We are not with the IFT any more and thus went independent at this time, but allot of the stories we have been working on still use the premise of carrying out more dangerous missions and things like that. So we stuck with that part of it.
As you can see we are not cannon to any shows, so are ship is unique to us, of course having the usual 2 nacelles, saucer, and stardrive section, etc.
Yes, there was an original Avalon Class and the original Grandeur NFC 90125 was more or less a Scout Reconnaissance type ship, different from what you are seeing here. In our stories when the original Grandeur was for the most part badly destroyed, we were the first ones in the Avalon class line to get the full upgrade to a Heavy Tactical Cruiser. For sure more beefier, more special weapons upgrades, and so on and so fourth. Thus while there were still some regular Avalon class ships around, it was decided to keep the Class and name it Avalon Class II and like most ships that get rebuild to a different upgrade we also became the USS Grandeur NFC 90125-A
Anyway I hope that answers some of your questions. Again we, the USS Grandeur was the first to get this new Heavy Tactical Cruiser upgrade so at this time there are none besides us with this design and style. As far as the old Avalon class and the ships in our stories at the time, there were 3 named... Avalon of course, Grandeur, and the Majestic. There was other names thought of based off our Renaissance/medieval period theme, but none were ever presented.