In other contexts, it can save a lot more than that. [K?SS], the example already shown, is a lot shorter (and a lot simpler) than [F?AA][W?DD].
S does end up representing a known piece, the Alibaba. There's currently no named piece (that I know of) related to T, but that doesn't mean that it's never going to be useful; someone might even find a reason to use [cTX-bsFX] (though I doubt I'd try anything more extreme than [cT-bN] even if it was currently supported).
In other contexts, it can save a lot more than that. [K?SS], the example already shown, is a lot shorter (and a lot simpler) than [F?AA][W?DD].
S does end up representing a known piece, the Alibaba. There's currently no named piece (that I know of) related to T, but that doesn't mean that it's never going to be useful; someone might even find a reason to use [cTX-bsFX] (though I doubt I'd try anything more extreme than [cT-bN] even if it was currently supported).