Will the SCD value also float? I would want at least one float for doing road work with a grading scraper.
Both the FD "Float Detent" and SCD "Self Canceling Detent" valves have detents in their forward most postion. Both valves operatate the exact same when NOT in their detent positions.
The FD will "float" when you push the lever all the way forward to the detent position. This is just like the "float" detent position of the FEL valve. When the FD valve is in the detent (float) position, fluid is NOT forced in any direction. Fluid is allowed to flow freely in either direction. An example of this is a batwing on a big mower. The float position allows the batwing to move up and down (to "flap" its wing if you will) to follow the contour of the land.
The SCD, when in the detent position, will force fluid to flow in one direction -- just as if you were holding the level forward manually. When the ram reaches its max position and the pressure builds, the valve will automatically cancel and the lever snaps back into the neutral position which in effect stops all fluid flow.
These two different types of valves operatate completely different in their detent positions. These also have nothing to do with the operation of a 3ph. If you are going to use these valves to operate hydraulics that are for use on the 3ph (the TnT is a perfect example -- which of course is what you are asking about), you will need to understand how the 3ph behaves (no down pressure, freely floats up, only lift pressure) and how the hydraulics used in conjunction with the 3ph behaves in order to achive the desired outcome(s).
Also, I don't have a TnT setup but I do have a big grading scraper and use it on my gravel drive. My 3ph lift arms have pins that can be rotated 90 degress to allow the lift arms to float. I use this "floating" position when I use my grading scraper. It works nicely.
I only have two remotes on my tractor. It came with one SCD and I added one FD when I ordered it... so I have one of each.
One thing to remember, if your hydraulic cylinder comes with a check-valve, like on my CCM hydraulic top link, the float position of your valve will not do anything. The check-valve will prevent the cylinder from floating.