my pedal technique involves pretty small movements up and down so as to avoid adding pedal noise.
Ah. At least that's not an issue on a DP, where pedal noise usually doesn't exist, or if it does, it is often a "feature" that can be adjusted or turned off.
On an acoustic if you accidentally stray a hair too high or low you will feel and hear and correct it but it won't be so blaringly obvious that it will ruin what you are playing.
On a digital piano you can't feel the transition so it is very easy to stray over the line from on to off inadvertently. When I play a digital without half-pedal I can tell you the effect is very jarring for me.
This could have at least as much to do with where the transition point between On and Off is (on a simple two-position pedal), as it does with whether the pedal sends any values in between.
Regarding your comments about the pedals, I could be wrong, but I don't think the pedals that are capable of partial pedaling send midi signals or any other digital information.
Correct. I didn't mean to imply otherwise. A simple pedal is an analog switch, open or closed, which the keyboard converts into MIDI 0 or 127. The half-pedaling capable pedals are sending a range of analog values which are than converted to 0, 127, or one or more points in between... the pedals, themselves, are not sending MIDI data, I agree.
As for whether *most* DP pedals are of the on/off or continuous variety, I suppose it's an empirical question. There aren't that many digitals around that don't do partial pedal any more so I don't know how one could think that on/off type pedals are common by any normal metric.
On/Off pedals have been the standard DP sustain pedal going back at least to the 1970s. They are also the same as footswitches that have been used for synths, workstations, drum machines, recording devices, organ rotary effects, etc., for just as long. (I am including the little square sustain pedals as well as the ones that are shaped like piano pedals... traditionally, their physical operation has been identical.) So that's most of what you'll find out there. Continuous pedals in a spring-back mechanism (as opposed to in an expression/volume pedal, which stays where you leave it) is a relatively recent development, and other than the pedals that come with the pianos that support it, there aren't a whole lot of them around. Probably in part because there is less use for them (as I said, the other kind is used for all kinds of things), they are more expensive, and there is probably less standardization/interchangeability among them.
edit: To that last point, if you look up "sustain pedals" on sweetwater, you'll see more switch pedals than half-damper pedals. And the switch pedals--as well as the switch functionality of the half-damper pedals--will work on all instruments (with the usual caveat that some instruments require normal-open and some require normal-closed; some pedals are switchable), while the half-damper functions are only listed as being certain to work on particular keyboards that are made by the manufacturer of the pedal.