Thanks for posting. I see you have also reached out to us directly via an email to firstname.lastname@example.org. I have just sent my reply to that email, and I post the body of my response below for the benefit of any one else following this thread. Please only reply to my direct response as that will help us keep everything in one place.
Body of direct response:
One quick thing to mention, we have not yet tested any of our products with the new HP Spectre with Thunderbolt 3 (our test unit is on order but has not yet arrived) so at this time we cannot guarantee its compatibility with any of our products.
In regard to potentially using our UD-ULTCDL Triple Display Docking system with the system, HP has a history of not allowing any devices other than HP products charge their systems. Until we have had a chance to test the Spectre with TB3, we will not know if our Triple Display dock can charge the system.
You also mention ‘displayport’ in your question but I think you may have meant DisplayLink (let me know if I am mistaken). The HDMI 2K output and the DVI output of the Triple Display dock are powered by a DisplayLink chip and will be able to drive two monitors at 1920x1080 resolution. The appearance of these displays should look indistinguishable from any other type of connection.
In regard to our Thunderbolt 3 Dual Display HDMI Adapter or upcoming Thunderbolt 3 docks, again we have not yet tested with the Spectre with TB3 so at this time we cannot guarantee compatibility. In reference to the Thunderbolt 3 Dual Display HDMI adapter, it only provides the two HDMI display outputs. If you needed other ports you would need to add a separate device.
In reference to the Thunderbolt 3 docks, the native output is a DisplayPort output that would require a DisplayPort to HDMI adapter to connect to a single HDMI display. You would need a separate USB-C to HDMI adapter to connect a second HDMI display.