Hi Zombielinux, The MST Hub is DP++ so it only requires passive adapters with an exception of using active adapters when you pass 1920×1200 resolution. In your case 1200×1920 in portrait mode is fine using passive adapters.
You can read more about the MST Hubs in our technology section.
I will be making more pages shortly so we can make more clear these questions. You can find the page here Welcome to Insights!

Thanks Paul!

I also see there are a few different 3×1 Hubs that you all produce. The 5300, 5300U, 5300H, and the 5300A. 

I’m trying to stay away from the 5300H because I may be getting some different monitors in the future. 

But between the three remaining, its kind of difficult to see which one would work in my application. 

The CSV-5300 is the same as the CSV-5300U, the later is our USA/Canada part number. The CSV-5300H is the HDMI version. 
Now, the CSV-5300A is our latest model, this one has the latest STDP 4320 chip from ST Micro and is DisplayPort 1.2a. Also all the latest models have a scan/reset button on the back of the device, making easier for your graphics controller to recognise it.
If you have more questions let me know.
Cheers

Fantastic. I’ll lay my hands on one of the CSV-5300A’s 

Thanks Paul!