Cracking the unit and city limits, and the amount of civs is of a wholly different level from cracking the map size and money limits. In principle, it would of course be possible, but only with considerably more effort. And even then, if someone would achieve that, that Civ2 version would become incompatible with any other Civ2 version, so you could throw all your savegames and all Civ2 scenarios in the dustbin (or create a converter).
That ResHack thingy is nice and all, but it does absolutely nothing when you have Civ2 FW or earlier (those are Win16 applications)!
Peregrine: About changing the DLL graphics... what GifX or ResHack do is allow you to replace an image in your DLL. If someone changes graphics in there and wants to add it to his scenario distribution, he has two possibilities:
1. include only the replacement graphic(s), and describe to the user how they can put the graphics in the DLL's themselves.
2. Include the entire changed DLL, but that dramatically increases the size of the download.
So, another suggestion for a utility (something the creator of GifX was actually working on too, but never finished):
Make a small utility that can automatically replace and backup the DLL graphics and so automates step 1. as I mentioned above.
Scenario creators would only need to include the GIF's and (a download link to) this little application. The scenario users would then only need to run that program to switch the graphics, and run it again to put the originals back in, or something along those lines.
Another thing about the DLL's: I think that even when using ResHack the palettes of the DLL graphics can't be changed (well, they can, but it will look all screwed up if you do). That severely limits what graphics can be put in as replacements.
About the apparent downgrade by Cedric... I don't think he has made it. Cedric has only ripped off Microprose and Hasbro by creating patches that illegally upgrade or downgrade your civ2 version.

He created a patch which can upgrade Civ2 classic or downgrade Civ2 ToT to Civ2 MGE. He also created a patch that upgrades Civ2 classic to Civ2 FW.
In any case, if anyone would make a "patch" that would downgrade MGE to FW, you would simply get FW, which means NO multiplayer.