my 2 cents 1st penny: I'm an old timer saddled with long-abandoned rules of grammar. I was taught to use AS for affirmation and SO for negation. For example, A is AS good as B, but not SO good as C. The only place I know where this rule is honored is Black Jack Davy. In every version I've heard the second horse is always "not SO speedy".
2nd penny: There is an interesting western version, called Clayton Boone I don't remember it exactly, but it goes something like this

Way out in old New Mexico
Along the Spanish line
I was working for old Clayton Boone
A man well past his prime

Well he rides in and asks of me
What's happened to my lady
I says to him she's quit your range
And runs with handsome Davy

Go saddle for me the ??? drum
With the coal-black mane and tail
Point out to me them fresh-laid tracks
And after them I'll trail

I rode upon a saddle fine
A saddle made of silver
My bridle rein of beaten gold
Not of your common leather

I rode in to the midnight sun
Till I seen the campfires burnin
I heard the sweetest mandolin
And the voice of Davy singin

Come home with me your own sweet bed
The sheets turned down so gaily
Do not forget my silver and gold
Do not forget your baby

(I'll not come home .. etc.)

Last night I slept with a mean ole man
In a golden room so stately
Tonight I'll sleep on hard cold ground
By the warm side of my Davy.

P.S. It seems that when the Child ballads get to my country they tend to be kinder to the womenfolk. Another example is Almeda Riddle's version of The 4 Marys versus the older versions, where Mary Hamilton is portrayed as wicked an unrepentant.