Sorry to jump in here, but I think there are some misconceptions with how this was added in and it's functionality (whether it's even needed), but mainly with the communication provided with this feature.
From you're description of why it was added, "for the people with no TDC down", isn't exactly right. Those same people still need a button/switch/something to assign TDC down/action so the TDC action/no action toggle offers no help to them.
What TDC action/no action does - is makes it easier for EVERYONE to use added functionality.
What it also does is highlight the total miscommunication that's happened here.
Regardless of TDC action/no action toggle being added, what should have been put across more was that there is newTDC functionality that was not known, that being, being able to hold down the TDC button to slew without designating a target.
TDC action/no action toggle was just added to make using that functionality easier.
@bthunder: - try it with the DMT, there is definite speed change (not at home so cannot confirm with T-POd)