Hey Bruce,
I had the same imaging scope and guidescope as you have used but I used an NEQ6 and a 7D, my results are similar to yours but I never had issues using the starshoot autoguider package at 1600mm, maybe PA or PE is your main issue...
I know it says LCM instead of LMC but every time i try to change it, flickr gives me an error...
https://www.flickr.com/photos/kriis__xx/9719713829/