My understanding is that Agnosticism = Soft Atheism = The position that one does not know one way or the other about the God question (and, not knowing, lacking evidence, one takes the default position that there is no God).
That would seem to cover it. And this gels with Huxley's intent, far as I can see.
What about the igtheist, the one who refuses to engage with the question at all since it isn't clear? I think igtheism is different from agnosticism, because the latter does take a position.
No, I don't think agnosticism is an 'in between position', as has been suggested here. I think it is no more and no less than soft atheism.
And my personal view (for what that is worth) is that this (agnosticism, or soft atheism) is the only reasonable position to hold. The hard atheist, who declares with near-certitude that there is no God, is just as unreasonable (IMO) as the theist who declares that they believe in God (that is, they are more or less certain that there is a God).
ETA : Re-reading what I just posted sets me thinking : Since the agnostic (or soft atheist) is different from the igtheist, what does that say about the former? Are they implicitly assuming some particular God idea? Are they referring to a general God conception? Might it be that they haven't considered this at all? I don't know! This much at least is clear : the truly blest is the apatheist, since they don't waste time and energy trying to figure all this out!