SolydXK Update Pack (UP) 2014.01.15 has now been released: check the update release announcement for some details about content and installation (but not a lot of details, honestly).
This is the first update pack released under a new schedule, which will see quarterly updates rather than monthly; the reasons for this change are explained in their UP process change news posting.
Although I am personally a bit disappointed, because I am selfish and like to get frequent updates, I can certainly understand their reasons for making the change, and if I had been in that position I might well have made the same decision.
I am in the process of installing the UP on my two SolydX/SolydK systems as I write this: the pack is rather large, and rather complex so it takes a while.
To install it, you start by clicking on the 'Update Manager' icon in the panel (a small shield, probably with a green check mark on it). Don't be fooled or confused when the updates window opens and tells you the system is up to date, you have to click Refresh to force it to look for the update pack.
There is an update to the update manager itself in this pack, so the first thing that comes up will be only that one item. After you install that, Update Manager will restart and you'll get the rest of the (very long) list. When you are asked during the update installation process if you want to replace one or two configuration files, the safe thing to do is say keep the existing file.
The update installation complete without any problem on both of my systems; on the Lenovo T400 with SolydK it took about 20 minutes, and on the Samsung N150 Plus with SolydX it took about 30 minutes.
Well worth the time and effort required: it's been more than a month since I installed SolydXK, and I am still very pleased with it.
As I said in my original post, it seems to be turning out to be pretty much what I had hoped LMDE would be originally. The update release announcement cited above also says that they are working on a new set of ISO images as well.