Anything special I need to do to move SPLAT/Melodyne to a new PC? Here's what I've built.

That is way underpowered lololol. Think that power supply alone could power Nasa. Any way I know melodyne will allow you to deactivate a system of you have already used the 2 device limit. I wish all would allow a 3 limit but also understand they need to make money. Enjoy that beast I'm very jelly :)

The last two times I got new PC's, I used Acronis True Image to make a complete mirror of the original disk drives.
Including all of the hidden data and folders.  It was supposed to be an exact copy of every single byte in the drive.
But both times, I had to end up reinstalling most of the software and plugins, and re-registering (re-authorizing) them.  And when you have 100 programs and plugins it's a huge PITA.   Even worse is when you run out of authorizations and you have to e-mail or phone the company to ask for additional authorizations.

Not the answer you're looking for, but if there's an easier way to transfer all your software to a new computer, I'd like to know about it too.

Assuming you are planning a clean install with a fresh copy of Windows, you won't have Windows activation issues.
 
But if you are migrating an existing OS and/or hard drive, you may have some hurdles, depending on what version/edition of Windows you have.
 
The other software licenses you have that are linked to the existing computer hardware will need to be reset/re-authorized.  Programs that use a software e-license manager will probably be OK.  As far as Melodyne goes, you can sign into your account via their website and de-authorize/re-authorize your product just fine.

There's an article on this in this month's SOS magazine (April)

VinylJunkie
There's an article on this in this month's SOS magazine (April)

This! I just finished reading it.
 
I used Acronis to clone my drive and it worked very well. I think AD2 was the only plugin I had to update the registration for, and that was pretty painless.
 

Steve do your self a favor : clean install of your os !
                                        goto asus : https://www.asus.com/us/Motherboards/X99-DELUXE-II/HelpDesk_Download/
                                      : Install the inf/chipset driver for win 10 : Intel_Chipset_V10.1.2.19 .. this driver from asus is key ..do not use INTEL's even if it is...newer !
                                      : Update the BIos : X99-DELUXE II BIOS 1504 ..
                                      : You are now good to install other drivers ..like nvidia ....
                                      : Make your old drive a slave in your system and pull back programs if you have to ..or
                                      : install them Clean... clean is best !
                                      : Go online and order a Asus TB lll card as this is the future of digital audio. TB lll is
                                      : supported on win 10 and will now support many Other Products, before unusable !
                                      : when the 8 core goes on sale buy it ! Enjoy your new Power House Ride !