This is going to be a LONG post.
I suggest you print it out or archive it.
I can make a suggestion, but you'll need an EXTERNAL drive with which to do it.
Here's how I'd try it (remember, I said "try", because yours is a "special case" and may involve considerable effort):
When the new iMac arrives, get it set up but DO NOT TURN IT ON YET, NOT EVEN TO SEE IF IT WORKS. This is important, hence the shouting. You do not want to begin the setup process until the background work has been done.
Next, I'd download CarbonCopyCloner, which is FREE to download and use for 30 days. Get it here:
http://www.bombich.com/download.html
(I suggest you do this right now to have it handy. DON'T run it until you're actually ready to begin).
Next, I'd connect the external drive. Get it formatted to Mac OS extended with Journaling enabled.
Now, open CCC.
Accept CCC's defaults for now.
In CCC's window, put your 1tb drive (with your home folder) on the left.
Put the external drive to the right of it.
Now, turn CCC loose and let it clone the 1tb drive to the external.
It will take a little while.
When done, close CCC and open the external and check it out.
It should "look just like" the internal -- it's a clone, right?
OK, now we're ready to begin transferring data.
Disconnect the external drive and connect it to the NEW iMac.
Press the new iMac's power-on button and let it get to the setup assistant.
Begin setup.
At the right moment, setup assistant will ask if you wish to migrate from another drive.
YES, you want to do this, so...
... "aim" setup assistant at the external drive (with your home folder on it).
Now, setup assistant will ask WHAT you wish to migrate, with these choices:
- apps (no)
- accounts (yes)
- settings (yes)
- data (yes)
You want everything checked EXCEPT for "apps".
When you've got things selected, let setup assistant "do its thing".
Does this work for you?
When done, you should be presented with a login screen, and after logging in it should look pretty much like the desktop on your OLD iMac.
Does it?
At this point, I believe setup assistant's job will be done (it will quit itself).
You're now "in the finder", logged into your account on the new iMac.
But....
....we're only halfway there, not done yet.
We still have to get the applications migrated. So...
Disconnect the external drive and take it back to the OLD iMac.
Once it mounts on the desktop, you'll need to open Disk Utility.
Now, you want to ERASE the external drive -- again, to Mac OS extended with journaling enabled.
Now it's empty and ready to go, once more.
Re-open CCC.
Now we're going to clone the 256gb internal SSD.
Same process as before.
Once that's done, take it back to the NEW iMac and connect it.
Since you're now logged into your account, setup assistant no longer works.
Instead, we'll try "Migration Assistant" (inside the utilities folder).
Open Migration Assistant, give it a moment to get ready.
Migration Assistant should present you with a window that is similar to the one in setup assistant, offering to migrate apps, accounts, settings, data.
BUT... this time, the ONLY thing you wish to migrate is .... applications.
So, check that ONLY, and then let MA do its thing.
When done, the 3rd-party apps (from the old iMac) should now be migrated over.
This should "get you to where you want to be".
BE AWARE that some apps may not run -- might require updating.
IF you're using apps that require special "keys" or registration, they -might- need to be re-authorized.
But if you migrated "from a clone", I'm going to guess that most stuff will "come across" just fine.
Final thought:
If you try this, please save this thread and come back and report on how it went.
It's nice to know if one's advice worked.