Suppose that, instead of block-moving mods adding special functionality to their own blocks, Forge changed TileEntity to add methods to move tile entities. By default they would probably read/write it to/from NBT as normal. People like you and Bluedart wanting to move all blocks would have to do less redundant work focused on other people's mods.
From what you said, it sounds like your client is using a different modpack version from the server. You might have better luck if you re-downloaded the server files.
I've started into implementing the list of effects, since they seem the least likely to be vetoed. So far I made a mostly-working telekinesis catalyst. Have a look at the awful-quality demo video here.
Does your GitHub repo have your latest source code in it? I'll see what I can do with the world gen stuff.
Gizmos has some custom inventories and a tile entity if you need an example. (I don't understand much of the code myself, I copied from the Forge wiki and changed it to do what I wanted of it)
There are Bukkit plugins that do roughly this, if you are thinking for a server. Alternatively, you can use RedPower frames to accomplish much of this.
If you delete the mod, all Dimensional Doors blocks, items, rifts, etc. will disappear. The rifts will no longer affect your server, but anyone who uses Dimensional Doors or is in a pocket dimension when you remove Dimensional Doors will be unhappy.
Mirrors would probably require a shader. It would be OK for people with good computers, but many of us with average computers would be unable to play the mod without miserable lag. Compatibility might become an issue, too.
Gizmos v0.6 is now available. It works with the new Tekkit dropped into the mods folder.
(Sorry for the double post, but IMO a major release deserves an announcement no matter who the last poster was)
Sounds good. Maybe transmuting across essence types is possible for a high price - something like 50% loss between similar essences and 80% loss between very different ones?