Thanks Henry.
Yes, this movement is more baroque in its style, but also has elements of early classical.
I experimented a little with the minor mode towards the end of the exposition, with which I tried to create an ominously charged sentiment but which returns to fresh pastures.
Ultimately the style is idiosyncratic of baroque and classical idioms, and the slow movement provides a reflective contrast to the more vibrant firs movement.
On your comment regarding form of the third movement, I had in fact considered writing a rondo but the ideas I currently have do lean towards sonata form. It was quite common for all movements of wider works to be in sonata form in the classical era, with exception to dance oriented ones (minute, scherzo). I suppose whether or not that becomes a detracting factor depends on how well it is executed.