1. On-site WYSIWYG
2. Tilt/swing effects
3. Time savings in post
4. System modularity
I would certainly agree with all of those points, and add that the usefulness of any of those added benefits varies depending upon what you are shooting (e.g. studio still life vs. fine art landscape, etc.) and film vs. digital back. I personally went with a tech camera for use in the field for landscape. They are not much heavier than a dslr or certainly not more so than a MF digital cam. The lenses are lighter. The work flow is more old school, slow and plodding. The other thing to consider is that the different manufacturers (Alpa, Arca, Cambo, Hartblei, Sinar) all implement tilt/swing and shift in different ways. Cambo probably got it the most right with the capability to tilt/swing simultaneously and yet there are not equal amounts of shift from center in the vertical axis. Alpa got the vertical shift right with the 12Max and shift adapter. Sinar may also have simultaneous tilt/swing, but I am not sure.
Also, focusing on a ground glass is a unique experience, good for some, not so good for others I imagine. The other thing to consider if shooting digital is that only three of the listed manufacturers have sliding backs (Arca, Harblei, Sinar). But then that is more weight and more possibilities for a decrease in precision parallel alignment of the back to lens over time. The degree of system modularity also varies amongst the manufacturers. Again, each system has strengths and benefits, and weaknesses with regard to the listed functionalities.
Regardless, I love using a tech camera in the field mostly because it fits my more contemplative work flow...and it is a heck of a lot lighter than any 4x5 I have ever owned...a good thing for any aging back.