Koussevitzky Concerto Form?

Hello all,

I have to write program notes for my recital, and I'm hearing conflicting information on whether or not the Koussevitzky Concerto is in Arch form (ABCBA) or sonata form (Expo with two themes, development, and recap/coda). What is y'alls take on this? I'm performing the whole piece with no break in between the 2nd and 3rd movement, so would this change the form of the piece?