Slider COMP dropped from the Op Create Dialog will not (in its default config) react to a python .click(uOrV) method. The panel value is actually getting updated, but since the updated Slider COMP uses the new value parameter instead of just it’s associated panel values, the internal panelexec DAT that is supposed to keep it in sync is missing the change, I presume because it is checking to see if the panel is being pressed on (aka is select panel value true) but it misses the one frame pulse that .onclick() gives.
Also, manually changing the slider COMP’s value parameter does not update the corresponding panel value - mostly because that panel value is not necessary if you are using the slider COMP with the new value par method, but I’m betting it was supposed to be built similar to the new Button COMP which does have a panelexec DAT and a parexec DAT to make sure the value par and the panel value stay in sync. The Button COMP does properly respond to the python .click() method.
Also, really nitpicking now, but the new Button and Slider COMPs don’t respect the “Resize Panel COMP Nodes to Controlpanel Aspect” preference being unchecked 
my OCD sheds a tiny tear