I assume you are cosidering the steel handle version, I have aus8a FRN handle type, although I also have Spyderco ats55 in Delica. If you search, recently there are two threads at least on topic of ats55 versus ats34 and, versus vg10.
My own opinion is that is excellent steel for Dragonfly, which is small folder with very keen, flat ground blade. I don't see why it would need to be tough in this size, no use prying with it, it should be strong enough with good Rc to withstand normal uses like paper, cardboard, string, paring apple, ect . In this size and for expected uses for small folder like this ,ats 55 should be considered "more than enough." It should offer longer wear resistance than my aus8a Dragonfly, which is very good for this small folder.
Good luck choosing,
Martin