Yes, this is the piano / violin version which was known as the 2nd Violin Sonata "The Romantic". There are some very slight differences between it and the orchestral version, mostly in the solo violin part, which is fiendishly difficult in both versions. The piano part is also extremely taxing. This is a very splendid contribution to Holbrooke's discography. The "Sonatina" is an early work, but attractive nonetheless, while the Horn Trio is a masterpiece IMHO.
I am assured by CPO that their plans to record the orchestral version of "The Grasshopper" have not been cancelled.