Some typical tests
I plugged in a Samsung T3 SSD external drive into one of the USB 3 ports of the dock and ran a Black Magic speed test. It is a bit slower than plugging the drive directly into the MBP, but it is still getting write speeds at about 285 MB/s and read speeds of around 340 MB/s, so it still works for my needs. My understanding is that if you use multiple ports (i.e. ethernet and USB) to transfer data simultaneously, you will lose speed on each port. I am using this for my home office, so I don't need super-speedy professional processes like transferring video over one port and moving large files on another via the dock. However, if you are in that situation, you may want to research the issue.
My setup and use cases
I did test the analog output on the front with some headphones, though I will never use that port since I have a headphone setup and the Onkyo that I already have setup in the room. However, it shows up as "USB Audio CODEC" on my MBP and I tested it and everything was loud and clear. I am not sure what DACs they are using in the dock, but it should satisfy most non-audiophiles.
Target Display Mode with 2011 iMac
Secondly, I ran into an issue when I used the two docks together with Target Display mode (Note: This allows the iMac to be used as a display) on my 2011 iMac. Quite often, I don't need to use the iMac as display for the MBP because I have a nice 4k monitor. However, I still like having the iMac in the office for casual use and because it is front and center on my desk it makes it an ideal location for being a display that I might want to occasionally use with the MBP.
With the Belkin Dock, I couldn't get target display mode to work. However, if I unplugged the Elgato from the dock and plugged it directly into the MBP, I was able to use the feature. For my needs, it is pretty easy just to plug in one more cable, so I am going to keep the two docks separated.
The Wrap Up
Other than that, the Belkin works great and I have a one cable solution for powering the 2016, 15 inch MBP (Touchbar) and for connecting all of my USB 3 drives, ethernet, and feeding two 4k displays. That being said, I will probably plug both docks directly into the MBP to get the option of adding the iMac to my array of displays and to leave open the option of connecting a thunderbolt 3 device into the freed up port on the Belkin.