The STD is actually something special.
Here's a review http://www.retrosynth.com/~analoguediehard/studio/effects/ada_std-1/
6 analog BBD chorus voices (extremely rare! the last time I saw a multi-tapped BBD pedal was in some obscure pedal reverb from the early 80s)
•huge sweep range for the chorus voices -- most analog pedals only go up to about ~15 ms max (20 if you're lucky); this one reaches up to 55 ms, with shorter voices "filling in" all the "gaps" in the intermediate ranges if you want
•each of the 6 mod delay taps can be activated individually, and panned left or right separately
•secondary modulation can be added to the main sweep, using the SWEEP MOD feature (I think this is similar to how the Eventide Modfactor works--"modulating the modulation")
•most uniquely among analog rack choruses, this is the only one I know of that allows you to set it up as a true stereo chorus or a wet/dry chorus--so you can make it sound more like a thick, multivoice chorus (1210/DimD/TSC/etc.) OR a Boss CE-1/5/CE-2W/MXR M234/etc. John Petrucci-style 7 ms static wet/dry split is also possible here.
•flanging is possible too--and you can select Taps #1, 3, or 6 to be the feedback taps (all are in different "time ranges," so you get radically different sounds based on just which tap # you choose). There's also a high-cut filter there to warm up/"soften" the flanging.
•the SWEEP MOD feature--at the right values--can really add a nice "CE-1" style "jump" in the modulation pattern, or a nice "faux Leslie" kind of feel (on faster speeds)