I think they would benefit from a download portal area to simplify things. No kid wants to mess with maven just to get a server jar. Simple is best IMO.
SpongeVanilla will get alpha builds soon. Then you’ll be able to install it just like SpongeForge. For now the only option is to compile it yourself or wait for the alpha builds to get available, though.
Or 3rd option: go with SpongeForge and just don’t install forge mods, it will allow Vanilla clients to connect and will behave the same as SpongeVanilla.
That’s the intention behind having the Vanilla and Forge options
Switching is possible as long as you stay away from forge mods (which you’ll do).
Plugins and configurations remain the same for both implementations, just copy them and your migration from SpongeForge to SpongeVanilla should be done.
I’d refer to SpongeForge as Cauldron successor and SpongeVanilla as Bukkit alternative.
Sponge won’t run Bukkit plugins though, but there’s an experimental plugins available to run them indirectly (Pore).
The CLI that Sponge offers is underused, in my opinion. It’s discouraged because we want people to understand the underlying components of the server (eg, not every problem you’ll have while running Sponge is an issue with Sponge).
However, if you’re running a server, there’s absolutely nothing wrong with downloading just the Sponge build, and running from the CLI: java -jar sponge.jar go
This will download and install all the required Forge components and then launch the server. This command can be used on subsequent runs as well.